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Engineering Data & Specifications

Marley / MCW / Table of Contents

Engineering Data

Schematic 6
Support 16
Noise Attenuator Option 18
Hoisting Info 19
Freeze Prevention 20
Water Quality 21

Specifications / Base

Base 22
Thermal Performance 22
Performance Warranty 22
Design Loading 23
Construction 23
Mechanical Equipment 23
Fill, Louvers and Drift Eliminators 24
Hot Water Distribution System 25
Casing 25
Access 25
Collection Basin 25
Warranty 25

Specifications / Options

Stainless Steel Options

Stainless Steel Collection Basin 26
All Stainless Steel Cooling Tower 26

Convenience and Safety Options

Top Access Platform 26
Ladder Extension 27
Ladder Safety Cage 27
Access Door Platform 27
Distribution System Access Platform 27

Control Options
Fan Motor Starter Control Panel 28
Vibration Limit Switch 29
Basin Heater 29
Fan Motor Variable Speed Drive 29
Marley Premium VFD System 30

Miscellaneous Options
Sound Control 32
Premium Efficiency Motor 33
Discharge Hood 33
Marley / MCW Cooling Tower /
4

■ Air Movement Package

Forward-curved centrifugal fans are dynamically balanced and mounted on tubular steel shafts

Fans are supported by roller-bearings mounted at both ends with heavy-guage steel supports.

Spherical roller bearings are rated at an L10 life of 50,000 hours.

Fan guard / Air-inlet screens are 16 gauge galvanized steel.

TEFC Fan Motor—1.15 service factor, variable torque, and specially insulated for cooling tower duty.

The MCW Series air movement package including the structural support—guaranteed against failure for a
period of five full years. The motor is warranted separately by the motor manufacturer.

■ Water Distribution System

Pressurized spray system distributes water evenly over the fill.

Low-clog polypropylene nozzles—delivers precise distribution of water over the fill area.

Marley MC thermoformed PVC film fill assembled into packs for ease of removal and cleaning.

Marley XCEL drift Eliminators—limit drift losses to no more than .005% of the design GPM flow rate.

■ Structure

Forced-draft, counter-flow design requires considerably less plan area than crossflow towers typically use.

Series 300 stainless steel, 316 stainless steel or heavy mill galvanized steel construction.

Factory assembled—ensures final field installation will be hassle-free.

Centrifugal fans and a fully-enclosed falling water area create one of the quietest cooling tower configurations
on the market.
Marley / MCW Cooling Tower / 5

MCW Series towers are galvanized steel,

factory assembled, forced draft,
counterflow cooling towers, designed to serve air
Pages 22 thru 25 indicate those paragraphs
which will result in the purchase of a basic cooling
tower—one that accomplishes the specified thermal
conditioning and refrigeration systems as well as performance, but which will lack many operation—and
light to medium industrial process loads on clean maintenance-enhancing accessories and features
water. The Marley MCW cooling tower is particularly that are usually desired by those persons who are
suited to the urban environment, reducing noise responsible for the continuing operation of the
while increasing energy efficiency and performance. system of which the cooling tower is part. It will also
The specifications portion of this publication not incorporate those standard materials which testing
only relates the language to use in describing an and experience has proven to provide acceptable
appropriate MCW cooling tower—but also defines longevity in normal operating conditions.
why certain items and features are important enough Pages 26 thru 31 provide paragraphs intended to
to specify with the intention of insisting upon add those features, components, and materials that
compliance by all bidders. The left hand column of will customize the cooling tower to meet the user‘s
pages 22 thru 31 provides appropriate text for the requirements.
various specification paragraphs, whereas the right
hand column comments on the meaning of the
subject matter and explains its value.
Marley / MCW / Engineering Data : Schematic 6

Use this data for preliminary layouts only.

Obtain current drawing from your Marley sales
representative.

The UPDATE web-based selection software

—available at spxcooling.com—provides MCW
Series model recommendations based on
customer's specific design requirements.

4'-13/16" 45/16" 2'-117/8"

INLET CL

H
INSTALLED
C HEIGHT
ACCESS
DOOR

OUTLET

SIDE ELEVATION AIR INLET ELEVATION

ALL MODELS MODELS 901116B - 901117F

45/16" 5'-1113/16" 45/16" 8'-1111/16"

H
INSTALLED
HEIGHT

AIR INLET ELEVATION AIR INLET ELEVATION

MODELS 901126F - 901127J MODELS 901136H - 901137K
 Marley / MCW / Engineering Data : Schematic 7

Design Shipping Weight

Nominal Dimensions
Model Motor Operating lb
Tons
note 2 hp Inlet / Outlet Weight Heaviest
note 3 C H M Weight/Cell
dia lb Section
901116B-1 18 1.5 7'-6" 8'-45⁄8" 97⁄16" 21⁄2"

901116C-1 20 2 7'-6" 8'-45⁄8" 97⁄16" 21⁄2"

901116D-1 23 3 7'-6" 8'-4 ⁄8"

5
9 ⁄16"
7
21⁄2" 1616 1279 741

901117D-1 26 3 8'-53⁄4" 9'-43⁄8" 97⁄16" 21⁄2"

901117F-1 31 5 8'-53⁄4" 9'-43⁄8" 97⁄16" 21⁄2"

901126F-1 45 5 7'-43⁄4" 8'-45⁄8" 97⁄16" 3"

901126H-1 50 7.5 7'-4 ⁄4"

3
8'-4 ⁄8"
5
9 ⁄16"
7
3"
2548 1843 1005
901127H-1 57 7.5 8'-45⁄8" 9'-43⁄8" 97⁄16" 3"

901127J-1 62 10 8'-45⁄8" 9'-43⁄8" 97⁄16" 3"

901136H-1 66 7.5 7'-53⁄8" 8'-45⁄8" 1'-115⁄8" 4"

901136J-1 75 10 7'-53⁄8" 8'-45⁄8" 1'-115⁄8" 4"

9011137H-1 75 7.5 8'-53⁄16" 9'-43⁄8" 1'-115⁄8" 4" 3486 2410 1270

9011137J-1 85 10 8'-5 ⁄16"

3
9'-4 ⁄8"
3
1'-11 ⁄8"
5
4"

9011137K-1 93 15 8'-53⁄16" 9'-43⁄8" 1'-115⁄8" 4"

39/16"

MAKEUP 1"M

OVERFLOW 2"F

DRAIN 2"F
1113/16" 1'-7 11/16"

6"

39/16" 1'-13/16"

PIPING CONNECTIONS
ALL MODELS

NOTE
1 Use this bulletin for preliminary layouts only. Obtain current 4 Standard overflow is a 2" dia. F connection located on the side
drawings from your Marley sales representative. All table data is per of the collection basin. Makeup water connection is 1" dia. M
cell. connection located on the side of the collection. A 2"F drain
2 Last numeral of model number indicates number of cells. Change connection is located on the side of the collection basin and two
as appropriate for your selection. 2"F drain connections are located on the basin floor.
3 Nominal tons are based upon 95°F HW, 85°F CW, 78°F WB and
3 GPM/ton. The Marley UPDATE web-based selection software
provides MCW model recommendations based on specific design
requirements.
Marley / MCW / Engineering Data : Schematic 8

Use this data for preliminary layouts only.

Obtain current drawing from your Marley sales
representative.

The UPDATE web-based selection software

—available at spxcooling.com—provides MCW
Series model recommendations based on
customer's specific design requirements.

4'-13/16" 45/16" 11'-115/8"

INLET CL

H
INSTALLED
C HEIGHT
ACCESS
DOOR

OUTLET

SIDE ELEVATION AIR INLET ELEVATION

ALL MODELS MODELS 901146K - 901147L

45/16" 17'-117/16"

H
INSTALLED
HEIGHT

AIR INLET ELEVATION

MODELS 901156K - 901157N
 Marley / MCW / Engineering Data : Schematic 9

Design Shipping Weight

Nominal Dimensions
Model Motor Operating lb
Tons
note 2 hp Inlet / Outlet Weight Heaviest
note 3 C H Weight/Cell
dia lb Section
901146K-1 102 2 @ 7.5 7'-6" 8'-45⁄8" 6"

901147K-1 117 2 @ 7.5 8'-53⁄4" 9'-43⁄8" 6" 4422 2978 1534

901147L-1 125 2 @ 10 8'-5 ⁄4"

3
9'-4 ⁄8"
3
6"

901156K-1 134 2 @ 7.5 7'-6 9⁄16" 8'-45⁄8" 6"

901156L-1 150 2 @ 10 7'-6 ⁄16"

9
8'-4 ⁄8"
5
6"
6297 4114 2066
901157L-1 170 2 @ 10 8'-63⁄8" 9'-43⁄8" 6"

901157N-1 187 2 @ 15 8'-63⁄8" 9'-43⁄8" 6"

97/16"

39/16"

MAKEUP 1"M

OVERFLOW 2"F

DRAIN 2"F
1113/16" 1'-7 11/16"

61/16"

39/16" 1'-13/4"

PIPING CONNECTIONS
ALL MODELS

NOTE
1 Use this bulletin for preliminary layouts only. Obtain current 4 Standard overflow is a 2" dia. F connection located on the side
drawings from your Marley sales representative. All table data is per of the collection basin. Makeup water connection is 1" dia. M
cell. connection located on the side of the collection. A 2"F drain
2 Last numeral of model number indicates number of cells. Change connection is located on the side of the collection basin and four
as appropriate for your selection. 2"F drain connections are located on the basin floor.
3 Nominal tons are based upon 95°F HW, 85°F CW, 78°F WB and 3
GPM/ton. The Marley UPDATE web-based selection software
provides MCW model recommendations based on specific design
requirements.
Marley / MCW / Engineering Data : Schematic 10

Use this data for preliminary layouts only.

Obtain current drawing from your Marley sales
representative.

The UPDATE web-based selection software

—available at spxcooling.com—provides MCW
Series model recommendations based on
customer's specific design requirements.

7'-101/2" 41/2" 41/2" 11'-7 3/4"

INLET
CL

H
INSTALLED
C HEIGHT

ACCESS
DOOR

OUTLET

SIDE ELEVATION AIR INLET ELEVATION

ALL MODELS MODELS 901546M - 901549P

41/2" 17'-7 13/16"

CL

H
INSTALLED
HEIGHT

AIR INLET ELEVATION

MODELS 901556N - 901558R
 Marley / MCW / Engineering Data : Schematic 11

Design Shipping Weight

Nominal Dimensions
Model Motor Operating lb
Tons
note 2 hp Inlet / Outlet Weight Heaviest
note 3 C H Weight/Cell
dia lb Section
901546M-1 214 25 12'-47⁄16" 13'-41⁄4" 8"

901546N-1 225 30 12'-47⁄16" 13'-41⁄4" 8"

901547M-1 239 25 13'-9 ⁄8"3

14'-9 ⁄16"
3
8"

901547N-1 253 30 13'-93⁄8" 14'-93⁄16" 8" 9416 6798 4012

901548N-1 270 30 13'-9 ⁄8"3

14'-9 ⁄16"
3
8"

901548P-1 298 40 13'-93⁄8" 14'-93⁄16" 8"

901549P-1 309 40 14'-99⁄16" 15'-93⁄8" 8"

901556N-1 286 2 @ 15 11'-91⁄2" 12'-93⁄8" 8"

901556P-1 315 2 @ 20 12'-4 ⁄16"7

13'-4 ⁄4"
1
8"

901556Q-1 336 2 @ 25 12'-47⁄16" 13'-41⁄4" 8"

13076 9078 5329
901557Q-1 379 2 @ 25 13'-9 ⁄8"3
14'-9 ⁄16"
3
8"

901557R-1 400 2 @ 30 13'-93⁄8" 14'-93⁄16" 8"

901558R-1 429 2 @ 30 13'-9 ⁄8"3

14'-9 ⁄16"
3
8"

1080

140

MAKEUP 1"M

OVERFLOW 3"F
DRAIN 2"F

470 858

255

130 440

PIPING CONNECTIONS
ALL MODELS

NOTE
1 Use this bulletin for preliminary layouts only. Obtain current 4 Standard overflow is a 3" dia. F connection located on the side
drawings from your Marley sales representative. All table data is per of the collection basin. Makeup water connection is a 1" dia. M
cell. connection located on the side of the collection. Drain is a 2"F
2 Last numeral of model number indicates number of cells. Change connection located on the side of the collection basin.
as appropriate for your selection.
3 Nominal tons are based upon 95°F HW, 85°F CW, 78°F WB and
3 GPM/ton. The Marley UPDATE web-based selection software
provides MCW model recommendations based on specific design
requirements.
 Marley / MCW / Engineering Data : Schematic 12

Use this data for preliminary layouts only.

Obtain current drawing from your Marley sales
representative.

The UPDATE web-based selection software

—available at spxcooling.com—provides MCW
Series model recommendations based on
customer's specific design requirements.

9'-9" 41/2" 8'-91/2"

INLET
CL

H
INSTALLED
C HEIGHT

ACCESS
DOOR

OUTLET

SIDE ELEVATION AIR INLET ELEVATION

ALL MODELS MODELS 901731L - 901738N

41/2" 12'-1" 41/2" 17'-7"

H
INSTALLED
HEIGHT

AIR INLET ELEVATION AIR INLET ELEVATION

MODELS 901746N - 901748Q MODELS 901756Q - 901758R
 Marley / MCW / Engineering Data : Schematic 13

Design Shipping Weight

Nominal Dimensions
Model Motor Operating lb
Tons
note 2 hp Inlet / Outlet Weight Heaviest
note 3 C H Weight/Cell
dia lb Section
901731K-1 142 15 12'-103⁄4" 14'-27⁄8" 8"

901732L-1 179 20 14'-0 ⁄8"

7
15'-5" 8"

901732M-1 191 25 14'-07⁄8" 15'-5" 8"

901736L-1 178 20 12'-10 ⁄4"

3
14'-2 ⁄8"
7
8" 9266 6290 3602

901736M-1 190 25 12'-103⁄4" 14'-27⁄8" 8"

901737N-1 218 30 14'-07⁄8" 15'-5" 8"

901738N-1 234 30 14'-103⁄8" 16'-21⁄2" 8"

901746N-1 261 30 12'-103⁄4" 14'-27⁄8" 8"

901747N-1 285 30 14'-07⁄8" 15'-5" 8"

901747P-1 314 40 14'-0 ⁄8"

7
15'-5" 8" 12148 8028 4798

901748P-1 337 40 14'-107⁄8" 16'-21⁄2" 8"

901748Q-1 357 50 14'-107⁄8" 16'-21⁄2" 8"

901756Q-1 381 2 @ 25 12'-103⁄4" 14'-27⁄8" 10"

901757Q-1 417 2 @ 25 14'-07⁄8" 15'-5" 10"

16998 10954 6256
901757R-1 437 2 @ 30 14'-07⁄8" 15'-5" 10"

901758R-1 469 2 @ 30 14'-107⁄8" 16'-21⁄2" 10"

5'-01/2"

1'-55/16"
51/2"

MAKEUP 11/2"M

OVERFLOW 11/2"M

81/2" 2'-9 3/4"

101/16"

51/8"
DRAIN 2"F

PIPING CONNECTIONS
ALL MODELS

NOTE
1 Use this bulletin for preliminary layouts only. Obtain current 4 Standard overflow is a 11⁄2" dia. M connection located on the side
drawings from your Marley sales representative. All table data is per of the collection basin. Makeup water connection may be 11⁄2" dia.
cell. M connection located on the side of the collection. Drain is a 2"F
2 Last numeral of model number indicates number of cells. Change connection located on the side of the collection basin.
as appropriate for your selection.
3 Nominal tons are based upon 95°F HW, 85°F CW, 78°F WB and 3
GPM/ton. The Marley UPDATE web-based selection software
provides MCW model recommendations based on specific design
requirements.
Marley / MCW / Engineering Data : Schematic 14

Use this data for preliminary layouts only.

Obtain current drawing from your Marley sales
representative.

The UPDATE web-based selection software

—available at spxcooling.com—provides MCW
Series model recommendations based on
customer's specific design requirements.

11'-93/4" 41/2" 41/2" 11'-7 3/4"

INLET
CL

H
INSTALLED
C HEIGHT

ACCESS
DOOR

OUTLET

SIDE ELEVATION AIR INLET ELEVATION

MODELS 901946N - 901949R

41/2" 17'-7 13/16"

INLET
CL

H
INSTALLED
HEIGHT

AIR INLET ELEVATION

MODELS 901956Q - 901959T
 Marley / MCW / Engineering Data : Schematic 15

Design Shipping Weight

Nominal Dimensions
Model Motor Operating lb
Tons
note 2 hp Inlet / Outlet Weight Heaviest
note 3 C H Weight/Cell
dia lb Section
901946N-1 251 30 12'-27⁄8" 13'-211⁄16" 8"

901946P-1 275 40 12'-27⁄8" 13'-211⁄16" 8"

901947N-1 280 30 12'-11 ⁄8"7

13'-11 ⁄16"
11
8"

901947P-1 309 40 12'-117⁄8" 13'-1111⁄16" 8"

901948N-1 307 30 13'-11 ⁄16"

11
14'-11 ⁄2"1
8" 13914 8588 4911

901948P-1 340 40 13'-1111⁄16" 14'-111⁄2" 8"

901949P-1 358 40 15'-45⁄8" 16'-47⁄16" 8"

901949Q-1 389 50 15'-45⁄8" 16'-47⁄16" 8"

901949R-1 416 60 15'-45⁄8" 16'-47⁄16" 8"

901956Q-1 375 2 @ 25 12'-27⁄8" 13'-35⁄8" 10"

901956R-1 401 2 @ 30 12'-27⁄8" 13'-35⁄8" 10"

901957Q-1 411 2 @ 25 12'-117⁄8" 14'-011⁄16" 10"

901957R-1 434 2 @ 30 12'-11 ⁄8"

7
14'-0 ⁄16"
11
10"

901958Q-1 463 2 @ 25 13'-1111⁄16" 15'-01⁄2" 10" 20437 12302 6536

901958R-1 491 2 @ 30 13'-11 ⁄16"

11
15'-0 ⁄2"
1
10"

901959R-1 513 2 @ 30 15'-45⁄8" 16'-57⁄16" 10"

901959S-1 567 2 @ 40 15'-4 ⁄8"

5
16'-5 ⁄16"
7
10"

901959T-1 600 2 @ 50 15'-45⁄8" 16'-57⁄16" 10"

7'-01/16"

51/2"

MAKEUP 11/2"M

OVERFLOW 11/2"M
DRAIN 2"F

1'-61/2" 2'-93/4"

101/16"

51/8" 1'-55/16"

PIPING CONNECTIONS
ALL MODELS

NOTE
1 Use this bulletin for preliminary layouts only. Obtain current 4 Standard overflow is a 11⁄2" dia. M connection located on the side
drawings from your Marley sales representative. All table data is per of the collection basin. Makeup water connection may be 11⁄2" dia.
cell. M connection located on the side of the collection. Drain is a 2"F
2 Last numeral of model number indicates number of cells. Change connection located on the side of the collection basin.
as appropriate for your selection.
3 Nominal tons are based upon 95°F HW, 85°F CW, 78°F WB and 3
GPM/ton. The Marley UPDATE web-based selection software
provides MCW model recommendations based on specific design
requirements.
 Marley / MCW / Engineering Data: Support 16

6" C 6"
CL ANCHOR ANCHORCL
13/16"
BOLT BOLT
ANCHORCL
BOLT

HOLES FOR
3/8"
DIA. ANCHOR
3'- 11 5/8"
BOLTS 4 REQD
CL ANCHOR
BOLT

A
13/16"
TOWER COLLECTION
BASIN- AIR INLET FACE

SUPPORTING STEEL
SINGLE CELL

Model C SUPPORT
90111 BY OTHERS
1'-1115⁄16"

90112 4'-1113⁄16" NORMAL

90113 GAUGE
7'-113⁄4"
90114 10'-115⁄8"
90115 16'-117⁄16"
VIEW A

NOTE
1 Use this bulletin for preliminary layouts only. Obtain current
drawings from your Marley sales representative for final design.
2 Purchaser to provide tower support complete with holes and anchor
bolts. Do not use studs! Anchor points must be framed flush and
level at top.
3 Tower may be placed on a flat concrete slab.
 Marley / MCW / Engineering Data: Support 17

13/16" C 13/16"

CL ANCHOR ANCHORCL
13/16"
BOLT BOLT
A
ANCHOR CL
BOLT

HOLES FOR
3/8"
DIA. ANCHOR
BOLTS 4 REQD
B

CL SUPPORT
CL ANCHOR

SUPPORT
BY OTHERS
BOLT

NORMAL
GAUGE

1 3/16" TOWER COLLECTION

BASIN- AIR INLET FACE
VIEW A

SUPPORTING STEEL
SINGLE CELL

Model B C D
90154 7'-8 ⁄16"
15
11'-6 ⁄16"
3
7'-815⁄16"

90155 7'-89⁄16" 17'-61⁄4" 7'-81⁄2"

90173 9'-6 ⁄16"

15 8'-8" 9'-71⁄4"

90174 9'-615⁄16" 8'-8" 11'-113⁄8"

90175 9'-615⁄16" 8'-8" 17'-51⁄2"

90194 11'-73⁄4" 11'-63⁄16" 11'-73⁄4"

90195 11'-73⁄4" 17'-61⁄4" 11'-73⁄4"

NOTE
1 Use this bulletin for preliminary layouts only. Obtain current
drawings from your Marley sales representative for final design.
2 Purchaser to provide tower support complete with holes and anchor
bolts. Do not use studs! Anchor points must be framed flush and
level at top.
3 Tower may be placed on a flat concrete slab.
 Marley / MCW Cooling Tower / Engineering Data : Schematic : Attenuators
18

E D

AIR INLET ELEVATION SIDE ELEVATION A

ALL MODELS

Dimensions
Model
A B C D E

3'-7 ⁄16"
5
3'-7 ⁄8"
7
3'-8 ⁄16"
5
4'-1 ⁄16"
3
2'-1115⁄16"
90111
5'-6 ⁄16"
15
3'-7 ⁄8"
7
5'-7 ⁄16"
15
4'-1 ⁄16"
3
2'-1115⁄16"
3'-75⁄16" 3'-77⁄8" 3'-85⁄16" 4'-13⁄16" 5'-1113⁄16"
90112
5'-615⁄16" 3'-77⁄8" 5'-715⁄16" 4'-13⁄16" 5'-1113⁄16"
3'-75⁄16" 3'-77⁄8" 3'-85⁄16" 4'-13⁄16" 8'-113⁄4"
90113
5'-6 ⁄16"
15
3'-7 ⁄8"
7
5'-7 ⁄16"
15
4'-1 ⁄16"
3
8'-113⁄4"
3'-75⁄16" 3'-77⁄8" 3'-85⁄16" 4'-13⁄16" 11'-115⁄8"
90114
5'-615⁄16" 3'-77⁄8" 5'-715⁄16" 4'-13⁄16" 11'-115⁄8"
3'-75⁄16" 3'-77⁄8" 3'-85⁄16" 4'-13⁄16" 17'-117⁄16"
90115
5'-615⁄16" 3'-77⁄8" 5'-715⁄16" 4'-13⁄16" 17'-117⁄16"
3'-75⁄16" 6'-111⁄2" 3'-85⁄16" 7'-101⁄2" 11'-713⁄16"
90154
5'-615⁄16" 6'-111⁄2" 5'-715⁄16" 7'-101⁄2" 11'-713⁄16"
3'-75⁄16" 6'-111⁄2" 3'-85⁄16" 7'-101⁄2" 17'-713⁄16"
90155
5'-6 ⁄16"
15
6'-11 ⁄2"1
5'-7 ⁄16"
15
7'-10 ⁄2"
1
17'-713⁄16"
3'-75⁄16" 6'-111⁄2" 3'-85⁄16" 8'-99⁄16" 8'-99⁄16"
90173
5'-615⁄16" 6'-111⁄2" 5'-715⁄16" 8'-99⁄16" 8'-99⁄16"
3'-75⁄16" 6'-111⁄2" 3'-85⁄16" 8'-99⁄16" 11'-115⁄16"
90174
5'-615⁄16" 6'-111⁄2" 5'-715⁄16" 8'-99⁄16" 11'-115⁄16"
3'-75⁄16" 6'-111⁄2" 3'-85⁄16" 8'-99⁄16" 17'-71⁄16"
90175
5'-615⁄16" 6'-111⁄2" 5'-715⁄16" 8'-99⁄16" 17'-71⁄16"
3'-75⁄16" 6'-111⁄2" 3'-85⁄16" 11'-93⁄4" 11'-713⁄16"
90194
5'-615⁄16" 6'-111⁄2" 5'-715⁄16" 11'-93⁄4" 11'-713⁄16"
3'-75⁄16" 6'-111⁄2" 3'-85⁄16" 11'-93⁄4" 17'-713⁄16"
90195
5'-615⁄16" 6'-111⁄2" 5'-715⁄16" 11'-93⁄4" 17'-713⁄16"

NOTE
1 Attentuators will result in an additional external resistance therefore 2 Critical noise applications must be referred to SPX Cooling
the fan will be unable to deliver the same airflow resulting in a small Technologies engineering.
reduction in performance.
 Marley / MCW Cooling Tower / Engineering Data : Hoisting
19

B
A
80°MAX D 80°MAX
C

Lower Module Upper Module

Model Weight Weight
A B C D
lb lb
90111 1'-8" 4'-1" 540 3'-0" 4'-1" 740
90112 4'-8" 4'-1" 840 6'-0" 4'-1" 1005
90113 7'-8" 4'-1" 1140 9'-0" 4'-1" 1270
90114 10'-10" 4'-1" 1445 12'-0" 4'-1" 1535
90115 8'-10" 4'-1" 2050 18'-0" 4'-1" 2065
90154 4'-1" 7'-10" 4010 11'-8" 7'-10" 2785
90155 10'-1" 7'-10" 5330 17'-8" 7'-10" 3750
90173 8'-3" 9'-9" 3600 8'-10" 9'-8" 2690
90174 4'-3" 9'-9" 4800 12'-0" 9'-8" 3230
90175 9'-0" 9'-9" 6255 17'-7" 9'-8" 4700
90194 4'-1" 11'-8" 4910 11'-8" 11'-8" 3675
90195 10'-1" 11'-8" 6535 17'-8" 11'-8" 5765

NOTE
1 Hoisting operations can be dangerous and suitable safety 3 Ensure that slings are of sufficient length so not to impose bending
precautions should be taken to protect personnel and the loads onto the casing—use of spreader bars is essential.
equipment being hoisted. 4 For overhead lifts or where additional safety is required, add slings
2 All hoisting equipment should be certified and comply with local and beneath the tower unit
national safety regulations.
Marley / MCW Cooling Tower / Engineering Data: Freeze Prevention 20

When the ambient air temperature falls below 32°F, the Indoor Storage Tank
water in a cooling tower can freeze. Marley Technical Report With this type of system, water flows from an indoor tank,
#H-003 “Operating Cooling Towers in Freezing Weather” through the load system, and back to the tower, where it is
describes how to prevent freezing during operation. Available cooled. The cooled water flows by gravity from the tower to
at spxcooling.com or ask your Marley sales representative for the tank located in a heated space. At shutdown, all exposed
a copy. water drains into the tank, where it is safe from freezing.
During shutdown, water collects in the cold water basin The amount of water needed to successfully operate
and may freeze solid. You can prevent freezing by adding heat the system depends on the tower size and GPM and on
to the water left in the tower—or, you can drain the tower and the volume of water contained in the piping system to and
all exposed pipework at shutdown. from the tower. You must select a tank large enough to
Electric Basin Heaters contain those combined volumes—plus a level sufficient to
An automatic basin water heater system is available maintain a flooded suction on your pump. Control makeup
consisting of the following components: water according to the level where the tank stabilizes during
operation.
• Stainless steel electric immersion heater(s).
—Threaded couplings are provided in the side of the
collection basin.
• NEMA 4 enclosure containing:
—Magnetic contactor to energize heater.
—Transformer to convert power supply to 24 volts for
control circuit.
—Solid state circuit board for temperature and
low-water cutoff.
Enclosure may be mounted on the side of the tower.
• Control probe in the collection basin to monitor water
temperature and level.
Heater components are normally shipped separately for
installation by others.
Note: any exposed piping that is still filled with water
at shutdown—including the makeup water line—should be
electrically traced and insulated (by others).
Marley / MCW Cooling Tower / Engineering Data: Water Quality 21

The MCW cooling tower can be a very effective air washer.

Atmospheric dust able to pass through the relatively small CAUTION
louver openings will enter the recirculating water system. The MCW cooling tower must be located at such
Increased concentrations can intensify systems maintenance distance and direction to avoid the possibility of
by clogging screens and strainers—and smaller particulates contaminated discharge air being drawn into building
can coat system heat transfer surfaces. In areas of low flow fresh air intake ducts. The purchaser should obtain
velocity—such as the collection basin—sedimentary deposits the services of a Licensed professional Engineer or
can provide a breeding ground for bacteria. Registered Architect to certify that the location of the
cooling tower is in compliance with applicable air
In areas prone to dust and sedimentation, you should
pollution, fire and clean air codes.
consider installing some means for keeping the collection
basin clean. Typical devices include side stream filters and a
variety of filtration media.

Water Treatment
Blowdown
To control the buildup of dissolved solids resulting from
Blowdown or Bleedoff is the continuous removal of a water evaporation, as well as airborne impurities and biological
small portion of the water from the open recirculating system. contaminants including Legionella, an effective consistent
Blowdown is used to prevent the dissolved solids from water treatment program is required. Simple blowdown may
concentrating to the point where they will form scale. The be adequate to control corrosion and scale, but biological
amount of blowdown required depends on the cooling range— contamination can only be controlled with biocides.
the difference between the hot and cold water temperatures
of the closed circuit— and the composition of the makeup An acceptable water treatment program must be
water. compatible with the variety of materials incorporated in a
cooling tower—ideally the pH of the recirculating water should
fall between 6.5 and 9.0. Batch feeding of the chemicals
directly into the cooling tower is not a good practice
since localized damage to the cooling tower is possible.
Specific startup instructions and additional water quality
recommendations can be found in the which accompanies
the cooling tower and also is available from your local
Marley sales representative. For complete water treatment
recommendations and services contact Marley Water
Resources, toll free at 877 800 0929 or contact your local
Marley sales representative.
 Marley / MCW Cooling Tower / Specifications: Base
22

Specifications Specification Value

1.0 Base:

1.1 Furnish and install a forced-draft, coun- ■ Your specification base establishes the type, configuration, base material,
terflow-type, factory assembled, film fill, and physical limitations of the cooling tower to be quoted. During the
industrial duty, galvanized steel, cooling planning and layout stages of your project, you will have focused your
tower. Unit shall consist of _____ cell(s), attention on a cooling tower selection that fits your space allotment, and
as shown on plans. The limiting overall whose power usage is acceptable. Limitations on physical size and total
dimensions of the tower shall be _____ operating horsepower avoid the introduction of unforeseen operational
wide, _____ long, and _____ high. Total and site-related influences. Specifying the number of cells, and the maxi-
operating horsepower of all fans shall not mum fan hp/cell will work to your advantage.
exceed _____ hp, consisting of_____ @
_____ hp motor(s). Tower shall be similar The benefit of a forced-draft counterflow cooling tower is that they
and equal in all respects to Marley Model are inherently easy to operate, access, and maintain. Forced-draft
_____________________. counterflow towers have all mechanical equipment located at low level
for easy access, and the water distribution system is accessible by sim-
ply removing the lightweight drift eliminator panels or fill access doors.
2.0 Thermal Performance:

2.1 The tower shall be capable of cooling ■ CTI Certification means that the
_____ GPM of water from _____ °F to cooling tower has been tested under
_____ °F at a design entering air wet- operating conditions and found to
bulb temperature of _____ °F. The ther- perform as rated by the manufac-
mal performance rating shall be Certified turer under those circumstances.
by the Cooling Technology Institute. It assures the buyer that the tower
is not intentionally or inadvertently
3.0 Performance Warranty: undersized by the manufacturer.

3.1 CTI Certification notwithstanding, the ■ However, CTI certification alone is not sufficient to assure you that the
cooling tower manufacturer shall guar- cooling tower will perform satisfactorily in your situation. Certification is
antee that the cooling tower supplied established under relatively controlled conditions, and cooling towers
will meet the specified performance seldom operate under such ideal circumstances. They are affected by
conditions when the tower is installed nearby structures, machinery, enclosures, effluent from other sources,
according to plan. If, because of a sus- etc. Responsible and knowledgeable bidders will take such site-specific
pected thermal performance deficiency, effects into consideration in selecting the coolling tower—but the speci-
the owner chooses to conduct an on- fier must insist by the written specification that the designer/manufacturer
site thermal performance test under the guarantee this “real world” performance. Any reluctance on the part of
supervision of a qualified, disinterested the bidder should cause you some concern.
third party in accordance with CTI or
ASME standards during the first year of
operation; and if the tower fails to per-
form within the limits of test tolerance;
then the cooling tower manufacturer will
pay for the cost of the test and will make
such corrections as are appropriate and
agreeable to the owner to compensate
for the performance deficiency.
 Marley / MCW Cooling Tower / Specifications: Base
23

Specifications Specification Value

4.0 Design Loading:

4.1 The tower and its components shall be ■ The indicated design values are the minimum allowables under accepted
designed to withstand a wind load of design standards. They give you assurance that the cooling tower can be
30 psf as well as .3g seismic load. The shipped, handled, hoisted—and ultimately operated in a normal cooling
cooling tower shall be designed to with- tower environment. Most MCW Series models will withstand signifi-
stand shipping and hoisting loads of 2g cantly higher wind and seismic loads. If your geographic location dictates
horizontal or 3g vertical. Handrails, where higher wind load or seismic load values, please make the appropriate
specified shall be capable of withstand- changes, after discussion with your Marley sales representative.
ing a 200 lb concentrated live load in any
direction and shall be designed in accor-
dance with OSHA guidelines.

5.0 Construction:

5.1 Except where otherwise specified, all ■ In the history of cooling towers, no other coating for carbon steel has
components of the cooling tower shall be exhibited the success and longevity of galvanization in exposure to the
fabricated of heavy-gauge steel, protected normal cooling tower water quality defined at left. No paints or electro-
against corrosion by G-235 galvanizing. statically-applied coatings, however exotic they may be, can approach
After passivation of the galvanized steel (8 galvanization's history of success.
weeks at pH 7-8, and calcium hardness
and alkalinity at 100-300 ppm each), the If extended longevity of the cooling tower is required—or unusually harsh
cooling tower shall be capable of with- operating conditions are expected—consider specifying stainless steel as
standing water having a pH of 6.5 to 9.0; either the base construction material, or the material utilized for specific
a chloride content up to 500 ppm as NaCl components of your choice. See Stainless Steel Options on page 16.
(300 ppm as Cl-); a sulfate content (as
SO4) up to 250 ppm; a calcium content
(as CaCO3) up to 500 ppm; silica (as
SiO2) up to 150 ppm; and design operat-
ing ranges up to 50°F. The circulating
water shall contain no oil, grease, fatty
acids, or organic solvents.

5.2 The specifications, as written, are intend-

ed to indicate those materials that will
be capable of withstanding the above
water quality in continuing service, as
well as the loads described in paragraph
4.1. They are to be regarded as minimum
requirements. Where component materi-
als unique to individual tower designs are
not specified, the manufacturers shall
take the above water quality and load
carrying capabilities into account in the
selection of their materials of manufac-
ture.

6.0 Mechanical Equipment:

6.1 Fan(s) shall be forward curved centrifu- ■ The Marley drive system features all-aluminum sheaves (pulleys), power
gal-type, which are statically and dynami- band belts, and long-life bearings for dependable service.
cally balanced. The fan impeller is manu-
factured from galvanized steel, blades are To reduce cost, some manufacturers may use TEAO motors, whose only
riveted to the center plate and inlet rings source of cooling is the flow of air produced by the cooling tower fan.
and have stay rods to ensure maximum They are sometimes applied at horsepowers significantly beyond their
nameplate rating.
➠
 Marley / MCW Cooling Tower / Specifications: Base
24

Specifications Specification Value

concentricity and rigidity. The stay rods Unless otherwise specified, motor speed will be 1800 RPM, 60 Hertz
are adjusted by the manufacturer during on standard models. If you prefer the operating flexibility of two-speed
the balancing operation and require no operation, please specify two-speed, single-winding motors which offer
field adjustment. Fan(s) shall be driven full and half speeds for maximum energy savings. Incidentally, two speed
through one-piece, multi-groove, V-belt, motors are a far better choice than separate “pony” motors which simply
pulleys, and spherical roller bearings. double the problems indicated above.
Bearings shall be rated at an L10 life of
50,000 hours, or greater. A hinged motor The value of a 5 year mechanical equipment warranty speaks for itself.
adjustment plate with threaded tensioning
bolts shall be installed to allow correct
belt tensioning.

6.2 Motor(s) shall be ____ hp maximum,

Totally Enclosed, 1.15 service factor, vari-
able torque, and specially insulated for
cooling tower duty. Speed and electrical
characteristics shall be ______ RPM,
single-winding, 3 phase, 60 hertz, ____
volts. Motor shall operate in the shaft-
horizontal position and nameplate horse-
power shall not be exceeded at design
operation

6.3 The complete mechanical equipment

assembly for each cell shall be supported
by a rigid, galvanized steel structural sup-
port that resists misalignment between
the motor and sheaves. The mechanical
equipment assembly shall be warranted
against any failure caused by defects in
materials and workmanship for no less
than five (5) years following the date of
tower shipment. This warranty is limited
to the fan, fan shaft, bearings, sheaves
and mechanical equipment support. The
motor, motor components and belt(s) are
warranted by their manufacturer.

7.0 Fill and Drift Eliminators:

7.1 Fill shall be cross-corrugated, counterflow ■ Fill modules can be removed for inspection and cleaning in accordance
film type, thermoformed from 15 mil thick with local anti legioinella guidelines.
PVC. Fill shall be assembled into modules
for ease of removal and cleaning. Fill shall Drift rate varies with design water loading and air rate, as well as drift
be supported on galvanized channel sec- eliminator depth and number of directional changes. A drift rate of
tions supported from the tower structure. 0.001% is readily available in standard configuration without premium
Drift eliminators shall be PVC, triple pass cost. If a lower rate is required, please discuss with your Marley sales
and shall limit drift losses to 0.005% or representative.
less of the design water flow rate.
 Marley / MCW Cooling Tower / Specifications: Base
25

Specifications Specification Value

8.0 Hot Water Distribution System:

8.1 A pressured spray system shall distribute ■ The combination of PVC piping and polypropylene nozzles is very resis-
water evenly over the fill. Header and tant to the build-up of scale and slime.
branch arms shall be PVC or steel with
polypropylene spray nozzles attached to
the branch arms by an integral screw
connection for ease of removal and
cleaning. A flanged connection on the
header shall be provided for attachment
to process piping.

9.0 Casing:

9.1 The casing shall be heavy gauge G-235

galvanized steel and shall be capable of
withstanding the loads described in para-
graph 4.1.

10.0 Access:

10.1 A large galvanized, rectangular access

door shall be located on both end pan-
els for entry into the cold water basin.
Rectangular panels are shall be provided
for access to the fan plenum area to
facilitate inspection and allow mainte-
nance to the fan drive system

11.0 Cold Water Collection Basin:

11.1 The collection basin shall be heavy-gauge ■ The MCW tower design offers side-suction as standard. Bottom outlets
galvanized steel and shall include the may be supplied to accommodate a variety of piping schemes. Unless so
number and type of suction connec- specified, the tower you may be asked to approve may only be available
tions required to accommodate the out- with one type of suction connection requiring you to redesign your piping
flow piping system shown on the plans. layout.
Suction connections shall be equipped
with debris screens. A factory installed, The sloping floor and low-level drain is valuable because it provides a
float operated, mechanical make-up valve way to achieve flush-out cleanability.
shall be included. An overflow and drain
connection shall be provided in each cell
of the tower. The basin floor shall slope
toward the drain to allow complete flush
out of debris and silt which may accumu-
late.

13.0 Warranty:

13.1 The MCW cooling tower shall be free

from defects in materials and workman-
ship for a period of twelve (12) from date
of initial use or eighteen (18) months
from the date of delivery, whichever
comes first.
 Marley / MCW / Specifications: Options 26

Specifications Specification Value

Stainless Steel Options

Stainless Steel Collection Basin: ■ The cold water basin is the only part of the tower that is subject to
periods of stagnant water, concentrated with treatment chemicals and
11.1: Replace paragraph 11.1 with the fol- customary contaminants. It is also the most expensive and difficult part
lowing: The collection basin shall be of any tower to repair or replace. For these reasons, many customers—
heavy-gauge Series 300 stainless steel particularly those who are replacing older towers—choose to specify
and shall include the number and type of stainless steel cold water basins.
suction connections required to accom-
modate the out-flow piping system shown
on the plans. Suction connections shall
be equipped with debris screens. A fac-
tory installed, float operated, mechanical
make-up valve shall be included. An
overflow and drain connection shall be
provided in each cell of the tower. The
basin floor shall slope toward the drain to
allow complete flush out of debris and silt
which may accumulate.

All Stainless Cooling Tower: ■ For pure resistance to corrosion—coupled with the capability to meet
stringent fire and building codes—there is no substitute for stainless
5.1 Replace paragraph 5.1 with the follow- steel. No paints or electostatically-applied coatings, however exotic they
ing: Except where otherwise specified, may be, can match stainless steel's ability to withstand adverse operating
all components of the cooling tower shall conditions.
be fabricated of heavy-gauge, series
300 stainless steel. The tower shall be
capable of withstanding water having a
chloride content (NaCl) up to 750 ppm; a
sulfate content (SO4) up to 1200 ppm; a
calcium content (CaCO3) up to 800 ppm;
silica (SiO2) up to 150 ppm; and design
operating ranges up to 50°F (). The cir-
culating water shall contain no oil, grease,
fatty acids, or organic solvents.

Convenience and Safety Options

Top Access Platform: ■ Periodic inspection and maintenance of a cooling tower distribution
system is fundamental to preserving maximum cooling system efficiency.
10.2 Add the following paragraph in the All cooling towers—crossflow or counterflow—are subject to clogging to
Access section: There shall be an access varying degrees by waterborne contaminants such as pipe scale and
platform at the top of the tower to allow sediment. Therefore, safe and easy access to these components is of
access to the drift eliminators and distribu- significant value to the operator.
tion system. The platform shall be free-
standing galvanized steel bar grating, sup- Access can be provided in a number of ways, including portable ladders
ported by galvanized steel framework. The or scaffolding, but for maximum safety and convenience, a field installed
platform shall be surrounded by a handrail, Marley access platform with guardrails is available to make this task as
kneerail, and toeboard designed accord- safe and user-friendly as possible. Further, its location on the side of the
ing to meet local safety requirements. tower does not add to the height of the unit, preserving architectural
Handrails and kneerails shall consist of integrity. It also saves the owner time and money, in that maintenance
1.66" O.D. x 15 gauge galvanized struc- personnel may devote their time to inspection rather than searching for
tural tubing, the handrail of which shall be ladders or erection of portable scaffolding.
capable of withstanding a 200 pound con-
centrated live load in any direction. Posts
are 2" x 2" square structural tubing and
 Marley / MCW / Specifications: Options 27

Specifications Specification Value

shall be spaced on centers of 8'-0" or less.

A ladder shall be permanently attached
to the platform and to the casing of the
tower, rising from the base of the tower to
the top of the handrail.

Ladder Extension: ■ Many cooling towers are installed such that the base of the unit is 2'-0"
or more above the roof or grade level. This makes it difficult to get up to
10.2 Add the following to the end of para- the foot of the attached ladder. The ladder extension alleviates this prob-
graph 11.2: Provide a ladder extension lem. Marley ladder extensions are available in standard 5'-0" and 11'-0"
for connection to the foot of the ladder. lengths.
This extension shall be long enough to
rise from the roof (grade) level to the
base of the cooling tower. The installing
contractor shall be responsible for cut-
ting the ladder to length; attaching it to
the foot of the cooling tower ladder; and
anchoring it at its base.

Ladder Safety Cage:

10.3 Add the following paragraph in the

Access section: A heavy gauge galva-
nized steel safety cage shall surround the
ladder, extending from a point approxi-
mately 7'-0" above the foot of the ladder
to the top of the handrail.

Access Door Platform: ■ Where cooling towers are installed on an elevated grillage or piers, it is
often difficult to get to—and through—the access door conveniently. This
10.4 Add the following paragraph in the platform provides easy, safe, and comfortable access to that door.
Access section: There shall be an access
platform at the base of the tower extend-
ing across the width of the casing. The
platform shall be galvanized steel bar grat-
ing, supported by galvanized steel frame-
work attached to the tower. The platform
shall be surrounded by a handrail, kneerail,
and toeboard.

Distribution System Access Door ■ This platform provides easy, safe and comfortable access to the access
Platform: door facilitating inspection of the fill, distribution nozzles and the under-
side of the drift eliminators.
10.5 Add the following paragraph in the
Access section: There shall be an access
platform at the level of the distribution
system access door. The platform shall be
galvanized steel bar grating, supported by
free-standinggalvanized steel framework
attached to the tower. The platform shall
be surrounded by a handrail, kneerail, and
toeboard.
 Marley / MCW / Specifications: Options 28

Specifications Specification Value

Control Options

Fan Motor Starter Control Panel: ■ If it is your opinion that the control system for the cooling tower be part
of the cooling tower manufacturer’s responsibility, we are in wholeheart-
6.4 Add the following paragraph in the ed agreement with you. Who better to determine the most efficient mode
Mechanical Equipment section: Each cell and manner of a cooling tower’s operation—and to apply a system most
of the cooling tower shall be equipped with compatible with it—than the designer and manufacturer of the cooling
a UL / CUL 508 listed control panel in a tower?
NEMA 3R or 4X outdoor enclosure capable
of controlling single-speed or two-speed Marley variable speed drives are also available for the ultimate in temper-
motors as required, and designed specifically ature control, energy management, and mechanical equipment longevity.
for cooling tower applications. The panel shall
include a main circuit breaker or main fused
disconnect with an external operating handle,
lockable in the off position for safety. Full
voltage non-reversing magnetic starter shall
be controlled with a thermostatic or solid-
state temperature controller. Door mounted
selector switches shall be provided to enable
automatic or manual control and wired for
120VAC control. Control circuit to be wired
out to terminal blocks for field connection to
a remote vibration switch, overload trip alarms
and remote temperature control devices. The
temperature controller shall be adjustable
for the required cold-water temperature. If
a thermostatic controller is used it shall be
mounted on the side of the tower with the
temperature sensing bulb installed in the cold
water basin using a suspension mounting
bracket. If a solid-state temperature controller
is used the controller will be door mounted
on the control panel. The solid-state tem-
perature controller will display two tempera-
tures, one for outgoing water and the other
for set point. Water temperature input shall
be obtained using a three-wire RTD with dry
well in the outlet water piping and wired back
to the solid-state temperature controller in
the control panel.
 Marley / MCW / Specifications: Options 29

Specifications Specification Value

Vibration Limit Switch: ■ Unless specified otherwise, a Marley M-5

vibration switch will be provided. The
6.5 Add the following paragraph in the requirement for manual reset assures that
Mechanical Equipment section: A single- the cooling tower will be visited to deter-
pole, double-throw vibration limit switch mine the cause of excessive vibration.
in a NEMA 4 housing shall be installed
on the mechanical equipment support for
wiring into the owner's control panel. The
purpose of this switch will be to interrupt
power to the motor in the event of exces-
sive vibration. It shall be adjustable for
sensitivity, and shall require manual reset.

Basin Heater: ■ The Marley basin heater components described at left represent our recom-
mendation for a reliable automatic system for the prevention of basin freez-
11.2 Add the following paragraph in the Cold ing. They are normally shipped separately for installation at the jobsite by
Water Basin section: Provide a system the installing contractor. When purchased in conjunction with the enhanced
of electric immersion heaters and con- Control System option, however, they are customarily factory-mounted and
trols for each cell of the tower to prevent tested.
freezing of water in the collection basin
during periods of shutdown. The system Submerged in basin water, in which zinc ions are present, copper
shall consist of one or more stainless immersion heaters must not be used. Insist upon stainless steel.
steel electric immersion heaters installed
in threaded couplings pro-vided in the The ambient air temperature that you insert in the specifications should be
side of the basin. A NEMA 4 enclosure the lowest 1% level of winter temperature prevalent at site.
shall house a magnetic contactor to ener-
gize heaters; a trans-former to provide
24-volt control circuit power; and a solid-
state circuit board for temperature and
low water cut-off. A control probe shall
be located in the basin to monitor water
level and temperature. The system shall
be capable of maintaining 40°F (4.4°C)
water temperature at an ambient air tem-
perature of _____ °F.

Fan Motor Variable Speed Drive:

Marley All Weather ACH550 System ■ Marley VFD drive systems are designed to combine absolute temperature
control with ideal energy management. The cooling tower user selects a
6.4 Add the following paragraph in the cold water temperature and the drive system will vary the fan speed to main-
Mechanical Equipment section when tain that temperature. Precise temperature control is accomplished with far
VFD is used with customers Building less stress to the mechanical equipment components. The improved energy
Management System: A complete UL listed management provides fast payback.
Variable Speed Drive system in a NEMA
1 indoor, NEMA 12 indoor or NEMA 3R Motors operated on a VFD shall carry a service factor of 1.0. When operating
outdoor enclosure shall be provided. The on a VFD, the drive parameters should be programmed to limit the current to
VFD shall use PWM technology with IGBT motor nameplate hp. Adjust the Motor specification accordingly.
switching and integrated bypass design.
VFD out put switching shall not cause
mechanical issues with gearbox teeth or
drive shafts. The VFD shall catch a fan
spinning in the reverse direction without
tripping. The panel shall include a main
disconnect with short circuit protection and
external operating handle, lockable in the
off position for safety. The VFD system shall

➠
 Marley / MCW / Specifications: Options 30

Specifications Specification Value

receive a speed reference signal from the

Building Management System monitoring
the tower fluid temperature. As an option to
receiving the speed reference signal from
a building management system, the drive
must have the capability to receive a 4-20
ma temperature signal from an RTD trans-
mitter. The VFD shall have an internal PI
regulator to modulate fan speed maintain-
ing set point temperature. The drive's panel
display shall be able to display the set-point
temperature and cold-fluid temperature on
two separate lines. The bypass shall include
a complete magnetic bypass circuit and
with capability to isolate the VFD when in
the bypass mode. Transfer to the bypass
mode shall be manual in the event of VFD
failure. Once the motor is transferred to
the by-pass circuit the fan motor will run at
constant full speed. The bypass circuit will
not modulate ON and OFF based on fluid
temperature. The application must be able
to handle very cold fluid temperatures while
the VFD is in a by-pass mode. Operator
controls shall be mounted on the front of
the enclosure and shall consist of start and
stop control, bypass/VFD selection, Auto/
Manual selections, manual speed control. To
prevent heating problems in the fluid coolo-
er fan motor and to assure proper gear
reducer lubrication the VFD system shall
de energize the motor once 25% motor
speed is reached and cooling is no longer
required. The fluid cooler manufacturer
shall supply VFD start-up assistance. Tower
vibration testing throughout the speed
range is required to identify and lockout any
natural frequency vibration levels which may
exceed CTI guidelines.

Marley Premium VFD System

6.4 Add the following paragraph in the

Mechanical Equipment section when VFD
is used as a stand alone system: A com-
plete UL listed Variable Speed Drive system
in a NEMA 12 indoor or NEMA 3R outdoor
enclosure shall be provided. The VFD shall
use PWM technology with IGBT switching
and integrated bypass design. VFD output
switching shall not cause mechanical issues
with gearbox teeth or drive shafts. The VFD
shall catch a fan spinning in the reverse
direction without tripping. The panel shall
include a main disconnect with short circuit
protection and external operating handle,
Marley / MCW / Specifications: Options 31

Specifications Specification Value

lockable in the off position for safety. The

system shall include a solid state, PI tem-
perature controller to adjust frequency
output of the drive in response to the tower
fluid temperature. The temperature of the
fluid and set point shall be displayed on
the door of the control panel. The bypass
shall include a complete magnetic bypass
circuit with capability to isolate the VFD
when in the bypass mode. Transfer to the
bypass mode shall be automatic in the
event of VFD failure or for specific trip
conditions allowing safe transfer of utility
voltage to the motor. Automatic bypass with
an earth ground condition is not allowed.
The bypass contactor shall be cycled on
and off while operating in bypass, to main-
tain the set-point temperature of the cold
water. The drive design shall be operated
as a stand-alone system without the need
for a BMS system. Operator controls shall
be mounted on the front of the enclosure
and shall consist of start and stop control,
bypass/VFD selector switch, Auto/Manual
selector switch, manual speed control, and
solid-state temperature controller. An emer-
gency bypass selector switch internal to the
panel allowing the fluid cooler fan motor to
be run at full speed shall be furnished. To
prevent heating problems in the fluid cooler
fan motor and to assure proper gear box
lubrication the VFD system shall de ener-
gize the motor once 25% motor speed is
reached and cooling is no longer required.
The VFD shall include de-icing logic with
auto canceling and adjustable time. Speed
in De-Ice mode shall not exceed 50%
motor speed. The fluid cooler manufacturer
shall supply VFD start-up assistance. Tower
vibration testing throughout the speed
range is required to identify and lockout any
natural frequency vibration levels which may
exceed CTI guidelines.
 Marley / MCW / Specifications: Options 32

Specifications Specification Value

Miscellaneous Options

Sound Control: ■ Sound produced by a standard MCW Series tower operating in an

unobstructed environment will meet all but the most restrictive noise limi-
1.2 Add the following paragraph under tations—and will react favorably to natural attenuation. Where the tower
Base: The cooling tower shall be quiet has been sized to operate within an enclosure, the enclosure itself will
operation, and shall produce an overall have a damping effect on sound. Sound also declines with distance—by
level of sound not higher than _______ about 5 or 6 dB(A) each time the distance doubles. Where noise at a
dB(A) measured at the critical location critical point is likely to exceed an acceptable limit, you have several
indicated on the plans. options—listed below in ascending order of cost impact:

• Where only a slight reduction in noise will satisfy—and the source of

concern is in a particular direction—merely turning the tower may be the
answer. Less sound emanates from the cased face of the tower than
does from the air intake face.

• In many cases, noise concerns are limited to night time, when ambient
noise levels are lower and neighbors are trying to sleep. You can usu-
ally resolve these situations by using two speed motors in either full /
half speed or full / 2/3 speed configuration, and operating the fans at
reduced speed without cycling “after hours”. (The natural night time
reduction in wet-bulb temperature makes this a very feasible solution in
most areas of the world, but the need to avoid cycling may cause the
cold water temperature to vary significantly.)

• Variable speed drives automatically minimize the tower's noise level

during periods of reduced load and/or reduced ambient without sacrific-
ing the system's ability to maintain a constant cold water temperature.
This is a relatively inexpensive solution, and can pay for itself quickly in
reduced energy costs.

• Where noise is a concern at all times (for example, near a hospital), the
best solution is to oversize the tower so it can operate continuously at
reduced (2/3 or ½) motor speed even at the highest design wet-bulb
temperature. Typical sound reductions are 7 dB(A) at 2/3 fan speed or
10 dB(A) at ½ fan speed, but larger reductions are often possible.

• The most extreme cases may require inlet and discharge sound attenu-
ator sections—however, the static pressure loss imposed by discharge
attenuators may necessitate an increase in tower size. Two stages of
inlet or discharge attentuators supported by the tower and designed
and tested for the most stringent requirements are available as an
option. See page 18.

The advantage is yours. You now have the choices you need to balance
your project’s performance, space and cost requirements with your
sound level needs for a win-win solution to your cooling system design.
Your Marley sales representative will be able to help you meet you
sound requirements.
 Marley / MCW / Specifications: Options 33

Specifications Specification Value

Premium Efficiency Motor:

6.3 Replace paragraph 6.3 with the follow- Where a tower is installed in a building well or there are high surrounding
ing: The fan and fan drive assembly for walls it is possible that a proportion of the hot and humid discharge air
each cell shall be supported by a rigid, will be drawn back into the fans thus increasing the inlet wet bulb tem-
welded, hot dip galvanized steel structural perature with detriment to the tower performance.
support that resists misalignment. The
mechanical equipment assembly shall be The tapered discharge duct is intended to increase the exit velocity by
warranted against any failure caused by up to 70% in order to reduce the effects of recirculation in some installa-
defects in materials and workmanship tions. Experience and sound judgement should be exercised to determine
for no less than five (5) years following when and if a duct is required.
the date of tower shipment. This war-
ranty shall cover the fan, speed reducer, If the surrounding walls are much higher than the tower discharge height
motor, drive shaft and couplings, and the then extensions to the tapered duct may be installed.
mechanical equipment support. The bear-
ing assemblies and V-belts shall be war-
ranted for 18 months.

Discharge Hood:

6.4 Add the following paragraph to the

Mechanical Equipment Section: There
shall be a galvanized steel tapered duct
on the discharge side of the tower. Drift
eliminators shall be repositioned into the
lower section of the duct.

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www.lenntech.com Fax. +31-152-616-289 material change without notice.
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