PX® Pressure Exchanger®, PX Q400

INSTALLATION, OPERATION, AND MAINTENANCE MANUAL

Energy Recovery Inc.

1717 Doolittle Drive, San Leandro, CA 94577
Tel: 1 510 483-7370
www.energyrecovery.com

Energy Recovery DOCUMENT NUMBER 80882-01-00

© Energy Recovery, Inc., 2022
 PX Q400 Energy Recovery Device

TABLE OF CONTENTS

1. INTRODUCTION ................................................................................................................. 3
ABOUT THIS MANUAL ......................................................................................... 3
DEVICE BASICS .................................................................................................... 3
PX DEVICE IN RO SYSTEMS................................................................................... 4
CIRCULATION PUMP WITH PX DEVICES ............................................................... 4
PX OPERATIONAL LIMITS ..................................................................................... 4
2. SAFETY ............................................................................................................................... 5
HIGH PRESSURE REMAINS AFTER SHUTDOWN .................................................... 6
LOW PRESSURE ISOLATION AND OVER-PRESSURIZATION .................................... 6
HYDROSTATIC TESTING ....................................................................................... 7
3. STORAGE AND HANDLING INFORMATION ......................................................................... 7
STORAGE AND HANDLING INFORMATION ........................................................... 7
LIFTING ............................................................................................................... 7
LIFTING EQUIPMENT .............................................................................................. 7
HORIZONTAL LIFTING PROCEDURE ........................................................................ 8
VERTICAL LIFTING PROCEDURE .............................................................................. 9
INSTALLATION .................................................................................................... 9
4. OPERATION........................................................................................................................ 10
FEEDWATER SUPPLY ........................................................................................... 10
START AND STOP PROCEDURES........................................................................... 10
STARTUP SEQUENCE .............................................................................................. 10
SHORT TERM SHUTDOWN SEQUENCE ................................................................... 11
LONG TERM SHUTDOWN SEQUENCE ..................................................................... 12
FEEDWATER FILTRATION .................................................................................... 12
FLOW CONTROL.................................................................................................. 12
LUBRICATION FLOW RATE ...................................................................................... 12
HIGH- AND LOW-PRESSURE FLOW RATES .............................................................. 13
FLOW BALANCE ...................................................................................................... 13
4.5. FLUSHING ........................................................................................................... 14
4.6. PURGE AIR .......................................................................................................... 15

Energy Recovery Document Number 80882-01-00 1

 PX Q400 Energy Recovery Device

5. SERVICE ............................................................................................................................. 15
SPARE PARTS AND TOOL KITS .............................................................................. 15
DISASSEMBLY PROCEDURE ................................................................................. 16
DISASSEMBLY PROCEDURE FOR THE PX DEVICE ON THE RACK OR PIPING ............. 17
PX DISASSEMBLY..................................................................................................... 18
ASSEMBLY PROCEDURE ...................................................................................... 24
CARTRIDGE ASSEMBLY ........................................................................................... 24
6. TROUBLESHOOTING .......................................................................................................... 30
PRELIMINARY PROCEDURES ................................................................................ 30
INSTRUMENTATION............................................................................................ 30
TROUBLESHOOTING GUIDE ................................................................................ 31
7. LEARNING MORE AND CONTACTING ENERGY RECOVERY.................................................. 33
8. REVISION LOG.................................................................................................................... 33

Energy Recovery Document Number 80882-01-00 2

 PX Q400 Energy Recovery Device

1. INTRODUCTION

About This Manual

This manual contains instructions for the installation and operation of Energy Recovery, Inc.
PX Q400 energy recovery devices for Reverse Osmosis (RO) systems. This information is
provided to ensure the long life and safe operation of your PX® Pressure Exchanger® (PX)
energy recovery device. This manual is intended for use by personnel with training and
experience in the installation and operation of fluid handling systems. For additional information
regarding using the PX device in RO systems, refer to Energy Recovery’s website:
www.energyrecovery.com or contact Energy Recovery customer service.

Device Basics

The PX energy recovery device transfers pressure energy from the RO high-pressure concentrate
reject stream to a low-pressure feedwater stream. It does this by putting the streams in direct,
momentary contact in the ducts of a rotor. The rotor is fit into a ceramic sleeve enclosed
between two ceramic end covers with precise clearances that, when filled with high-pressure
water, create an almost frictionless hydrodynamic bearing. The rotor spinning inside the
hydrodynamic bearing is the only moving part within the device.

C
F I

B H

Figure 1-1: Typical flow path of RO system with PX technology

Energy Recovery Document Number 80882-01-00 3

 PX Q400 Energy Recovery Device

PX Device in RO Systems

Figure 1-1 illustrates a typical flow schematic for a RO system equipped with a PX device. There
are two independent flow paths in the PX device, the low-pressure (LP) side [B to H] and the
high-pressure (HP) side [G to D]. The reject concentrate from the RO membranes [G] passes
through the PX device or an array of devices operating in parallel. The pressure of the
concentrate reject is transferred directly to a portion of the incoming feedwater at up to 98%
efficiency. This pressurized feedwater stream [D], which is nearly equal in volume and pressure
to the concentrate reject stream [G], passes through a circulation pump. The circulation pump
propels flow in the high-pressure loop [E-F-G-D] at a rate controlled by either a variable
frequency driver on the motor or a control valve at the discharge of the circulation pump. Fully
pressurized feedwater from the circulation pump merges with flow from the high-pressure
pump discharge [C] to feed the membranes [F].

Circulation Pump with PX Devices

In the typical RO system illustrated in Figure 1-1, a circulation pump is required to move water
through the membranes and PX device or array. The high-pressure flow through the PX unit(s)
is controlled by either a variable frequency drive operating the circulation pump or a flow control
valve at the circulation pump discharge. Recommended practice is to use a slightly oversized
circulation pump to accommodate for the projected range of concentrate flow and head
requirements. The head requirements are a sum of the pressure losses from the membrane,
piping, and PX device differential pressure (head). Seasonal variations, membrane fouling, and
other process variations should also be considered when sizing your circulation pump. Energy
Recovery carries a line of circulation pumps with capacities from 20 gpm (4.5 m3/hr) up to 2,200
gpm (500 m3/hr). Energy Recovery circulation pumps can be installed on the same manifold to
run in parallel to achieve higher capacities.

PX Operational Limits

Successful operation of the PX Q400 energy recovery device requires observation of some basic
operating conditions and precautions. The PX unit must be installed and operated in accordance
with this manual and good industrial practice to ensure safe operation and a long service life.
Failure to observe these conditions and precautions can result in reduced service life, damage

Energy Recovery Document Number 80882-01-00 4

 PX Q400 Energy Recovery Device

to the equipment, and/or harm to personnel. For operational conditions, refer to the Technical
Data Sheet of the product. Table 1-1 provides a summary of system performance limits.

Table 1-1: System Performance Limits

Operational values limits
Parameter
English Units Metric Units

Maximum high pressure (HP IN or HP OUT) 1,200 psig 82.7 bar

Maximum feedwater inlet pressure (LP IN) 145 psig 10 bar

Storage, operating, and feedwater temperature range 33-120 °F 1-49 °C

pH range 1-12 (short term at limits)

Further information about PX or other Energy Recovery products or service can be found by
contacting Energy Recovery at:

Energy Recovery Inc.

1717 Doolittle Drive, San Leandro, CA 94577
Tel: 1 510 483-7370
www.energyrecovery.com

For parts and/or inquiries, please e-mail: aftermarketsales@energyrecovery.com. Be sure to

include model and serial number along with company name and location in the e-mail.

2. SAFETY

The PX device is designed to provide safe and reliable service; however, it is used in a high-
pressure industrial process. Operations and maintenance personnel must follow the basic safety
rules associated with high-pressure equipment and seawater RO processes. Proper installation
and maintenance of shutdown devices and over-pressure and over-flow protection equipment
are an essential part of any RO system. Operation of the PX device outside of the designed
operating range can result in damage and may be unsafe.

Energy Recovery Document Number 80882-01-00 5

 PX Q400 Energy Recovery Device

NOTE These flags denote highlighted items.

CAUTION These flags denote items that, if not strictly observed, can result in
damage or destruction to equipment.

DANGER These flags denote items that, if not strictly observed, can result in
serious injury to personnel.

The flags shown and defined below are used throughout this manual. They should be given
special attention when they appear in the manual.

High-Pressure Remains After Shutdown

The high-pressure section of a RO system equipped with a PX energy

DANGER recovery device can remain pressurized after shutdown. Pressure
decreases as water slowly flows through the hydrodynamic bearing of the
PX unit. If more rapid system depressurization during shutdowns is required, the system should
be designed with accommodating valves and piping. Always make sure the RO system is fully
depressurized before disconnecting any piping or equipment.

Low-Pressure Isolation and Over-Pressurization

If the low-pressure side of the PX energy recovery device is isolated before

DANGER the high-pressure side is depressurized, the PX unit or the low-pressure
piping may be damaged by over-pressurization. High-pressure water will
seep through the PX device’s hydrodynamic bearing to low-pressure regions in the PX unit. To
prevent this over-pressurization scenario, use appropriate pressure relief valves, rupture disc
and/or depressurization procedures.

Energy Recovery Document Number 80882-01-00 6

 PX Q400 Energy Recovery Device

Hydrostatic testing

The PX shall not be subjected to hydrostatic testing outside of ERI’s test

DANGER facility. If hydrostatic testing of the plant piping and machinery is needed,
please remove the PX before doing so. Failure to do so may cause damage
to the device and/or injury.

3. STORAGE AND HANDLING INFORMATION

Storage and Handling Information

PX devices are packed with plugs installed on the connection ports. Keep the plugs in place until
the unit is to be fitted to the piping. This will keep the inside of the unit clean.

Follow these guidelines to reduce the potential for damage:

• The PX units must never be exposed to temperatures below 33F (1C) or above 120F (49C)
during storage or operation. If possible, store in a climate-controlled building or
warehouse.
• Avoid direct sunlight, rain or weather.
• Never lift or support the units with the end ports or side ports.
• Use a crane for lifting whenever one is available.

Lifting
Always use caution when working with heavy objects – The ERI PX-Q400
DANGER weighs approximately 360 LBS (164 KG) – and can be difficult to move and
manipulate.

Lifting Equipment

• Overhead Lift Machine (fork lift, overhead crane, floor crane)

o Minimum rating of 500 Lbs (227kg)
• Qty two (2) Flat-Eye Web sling
o Minimum rating – 1200 lbs (545kg)
o Minimum length – 9 ft (2.7m)

Energy Recovery Document Number 80882-01-00 7

 PX Q400 Energy Recovery Device

Horizontal Lifting Procedure

1) Space two (2) Flat-Eye Web Sling along the outer diameter of the PX as shown in Figure
3-1. Ensure slings are equally spaced with respect to the center-plane of the PX.
2) One sling can be used if configured as “Double Choker Hitch” shown in Figure 3-2.

Center-Plane

Figure 3-1: Space slings evenly along the PX housing. Figure 3-2: Single sling Double Choker Hitch method

3) Once unit is properly strapped it can be lifted and transported, to final destination,
carefully using either of these methods:
a. Overhead lift and/or Jib Crane
b. Fork Lift
c. Floor Crane

Energy Recovery Document Number 80882-01-00 8

 PX Q400 Energy Recovery Device

Vertical Lifting Procedure

1) Wrap the PX using the single Sling “Choker” method shown in Figure 3-3.
2) Place Sling below top side-port shown in Figure 3-4. Carefully lift and place unit as
required.

Figure 3-3: Single Choker method Figure 3-4: Single sling use on PX

Installation

PX devices can be installed and operated in any orientation. Each unit has four connections
labeled HP IN, HP OUT, LP IN, and LP OUT.

• HP IN is the high-pressure concentrate inlet.

• HP OUT is the high-pressure feedwater outlet to the circulation pump.
• LP IN is the low-pressure feedwater inlet.
• LP OUT is the low-pressure concentrate outlet.

The PX unit must be supported by its housing and not by the pipe fittings. Prevent the PX unit
from supporting piping or manifolds. The PX device should be kept in its original packing until

Energy Recovery Document Number 80882-01-00 9

 PX Q400 Energy Recovery Device

the initial startup of the RO train. Proper piping, piping support, and housing support must be
employed to minimize external stresses on all pipe fittings. Use shims to support and align the
housing. Suitable flexible couplings should be used for joining fittings and piping. Use only water-
soluble lubricants such as glycerin on coupling gaskets; do not use grease. Please request
dimensional drawings of a PX device and a piping detail for use for piping, manifold, and support
rack design.

Prior to installation of the PX device, all associated piping should be thoroughly flushed to assure
that no debris enters and/or damages the PX unit. Temporary installation of basket strainers at
both inlets to the PX device or PX device array can be used.

CAUTION Thoroughly flush associated piping with clean water before installing the
PX unit. Foreign material entering the unit may cause damage.

4. OPERATION

Feedwater Supply

Standard RO process chemicals are not harmful to the PX.

Start and Stop Procedures

The following procedures are general guidelines for the startup and shutdown of PX unit
systems. Procedure details will vary by plant design. Contact Energy Recovery if your process
design significantly differs from that shown in Figure 1-1. Always ensure that the operating limits
listed in Section 1.5 are followed.

Startup Sequence

1. All valves should be in their normal operating positions.

Energy Recovery Document Number 80882-01-00 10

 PX Q400 Energy Recovery Device

2. Start the feedwater supply pump. The feed flow through the PX unit(s) may or may not
cause the rotor to begin to rotate. Rotation will produce a humming sound that is audible
at close proximity to the PX unit(s).
3. Adjust the feedwater flow to the desired flow rate using the low-pressure outlet flow
control valve (FCV).
4. Open air vent valves to vent the high-pressure piping. This is necessary to allow air to
escape the system and to allow the high-pressure piping to fill with water pushed through
the high-pressure pump by the feedwater supply pump.
5. After the high-pressure piping is full of water, start the circulation pump. Rotor speed will
increase. Bleed any remaining air from the system.
6. Adjust the high and low-pressure flows to the PX unit to make them equal.
7. After the feedwater supply and circulation pump have run for sufficient time to purge all
air from the system, start the high-pressure pump. The RO system pressure will increase
to the point where the permeate flow will approximately equal the flow from the high-
pressure pump. The sound level from the PX unit will increase. Small variations in sound
level and rotor speed are normal.
8. Close the air vent valves.
9. Verify that pressure at the device low-pressure outlet exceeds minimum requirements.
10. Verify the high and low-pressure flow rates. Adjust flows as necessary to achieve balanced
flow to the PX units.

Short Term Shutdown Sequence

1. Throttle the LPOUT FCV to avoid overflow in the LP side of the unit when the high-
pressure pump is turned off.
2. Shut off the main high-pressure pump.
3. Wait until the system pressure drops to the osmotic pressure of the seawater, e.g. 400
psig (28 bar).
4. Shut off the circulation pump.
5. Shut off the feedwater supply pump.
6. If necessary, open a purge valve to expedite depressurization.

Energy Recovery Document Number 80882-01-00 11

 PX Q400 Energy Recovery Device

Long Term Shutdown Sequence

If the process is to be shut down for long term (the time frame depends on the characteristics
of the RO system and feedwater), the RO system including the PX units must be thoroughly
flushed with fresh water to remove any salt, and precautions should be taken to inhibit
biological growth. The high-pressure and low-pressure sides of the PX unit must be flushed
separately. The low-pressure side should be flushed with fresh water through the feedwater
feed line to the PX unit and to the concentrate drain. The high-pressure flush is typically
performed by circulating water through the PX unit and the membranes using the circulation
pump. Lubrication flow for the PX device rotors must be provided through the high-pressure
pump or some other injection point in the high-pressure loop during fresh water flushing. The
PX units should receive a final flush with the same solution used to preserve the RO membranes.

Feedwater Filtration

Like the RO membranes, the PX device requires filtered water. Particulates entering the PX
device are passed through to the membranes. Particles entering the PX device may also prevent
the rotor from spinning and can effect performance, resulting in the need to service the device.
The PX device filtration requirement applies during commissioning, normal operation, as well as
the membrane Clean in Place (CIP) process; refer to the technical data sheet for filtration
requirements.

Flow Control

Flow rates and pressures in a typical RO plant will vary slightly over the life of a plant due to
temperature variations, membrane fouling, and feed salinity variations. The PX unit’s rotor is
turned by the flow of fluid through the device. The speed of the rotor is self-adjusting over the
PX unit’s operating range. The ratio of the high and low-pressure flow rates affects the degree
of mixing between the feedwater and concentrate streams that occurs within the unit.

Lubrication Flow Rate

In a PX device, some of the high-pressure water flows through the hydrodynamic bearing to low-
pressure regions in the assembly. The lubrication flow rate varies with system pressure
according to the PX’s performance curves. If the PX device has a damaged o-ring or is damaged

Energy Recovery Document Number 80882-01-00 12

 PX Q400 Energy Recovery Device

by debris, overflow, or insufficient discharge pressure, excess lubrication flow may occur.
Monitoring lubrication flow is a good way to check the integrity of an operating PX unit.
Lubrication flow can be monitored using any of the following three methods:

• Measure the flow rate of the low-pressure feedwater to the high-pressure pump and the
flow rate of the permeate. The difference is approximately the lubrication flow rate.
• Measure the flow rate of the high-pressure concentrate to the PX unit and the high-
pressure feedwater from the PX unit. The difference is approximately the lubrication flow
rate.
• Measure the flow rate of the low-pressure concentrate from the PX unit and the low-
pressure feedwater to the PX unit. The difference is approximately the lubrication flow
rate.
Please note that this method of monitoring is to help establish trends. The value obtain may not
be exact.

High- and Low-Pressure Flow Rates

The high-pressure flow through the PX unit is set by adjusting the circulation pump with a
variable frequency drive or with a flow control valve and verified with a high-pressure flow
meter. The flow rate of the high-pressure feedwater out of the PX unit equals the flow rate of
the high-pressure concentrate to the PX unit minus the bearing lubrication flow.

The low-pressure flow through the PX unit is controlled by the feedwater supply pump and a
control valve in the concentrate discharge from the PX unit(s). This valve also adds backpressure
on the PX device required to prevent cavitation. The low-pressure flow rate must be verified
with a flow meter. The flow rate of the low-pressure concentrate from the PX unit equals the
flow rate of the low-pressure feedwater to the PX unit plus the bearing lubrication flow rate.

Flow Balance

The high and low-pressure flows to and from the PX device should be equal or “balanced” for
optimum RO operation. Operating the PX unit with unbalanced flows can result in higher
contamination of the feedwater feed by the concentrate reject. Balanced flows help limit the
mixing of concentrate with the feed. A feedwater inlet flow that is much less than the feedwater

Energy Recovery Document Number 80882-01-00 13

 PX Q400 Energy Recovery Device

outlet flow will result in lower quality permeate, increased feed pressure, and higher energy
consumption. For more information refer to Energy Recovery document 80088-01 Mixing
Technical Bulletin or contact Energy Recovery customer service.

4.5. Flushing

There are two types of flush: Feedwater Flush and Fresh Water or Permeate Flush. Regardless
of the flush water used, all parts of the PX device must be flushed, i.e. low-pressure flow
channels, high-pressure flow channels, and lubrication channels.

Feedwater Flushing is part of a normal shutdown sequence as described in Section 4. After both
permeate and concentrate production have ceased, flow on both the high-pressure and low-
pressure sides of the PX devices continues. The flow path of the Feedwater Flush, with reference
to Figure 1-1, is B-C-D-E-F-G-H driven by the feedwater pump and the circulation pump. A
Feedwater Flush is typically continued until conductivity measurements at process locations G
and H are satisfactory (TDS close to feedwater TDS).

A Permeate Flush or Fresh Water Flush is performed on a partially or fully depressurized system.
This is accomplished by introducing permeate simultaneously to the PX device low-pressure
inlet [B] and either to the high-pressure pump inlet [A] or through some other injection point
such as a CIP connection. Permeate may be produced during this flushing process. If so, it may
be necessary to block permeate flow to divert lubrication flow through the PX devices. The
circulation pump must be run to flush HP side of the PX device (s).

For more detail information refer to relevent Energy Recovery technical bulletins.

Energy Recovery Document Number 80882-01-00 14

 PX Q400 Energy Recovery Device

4.6. Purge Air

Entrained or trapped air or other gases must always be purged from the RO system before
pressurizing the system. Entrained air in a pressurized system can result in damage to the PX
unit. Prior to pressurizing the RO system, vent or flush for sufficient time to allow for the removal
of all air from the RO system.

CAUTION Entrained or trapped air must be purged from the RO system before every
pressurization.

5. SERVICE

Spare Parts and Tool Kits

The PX Q400 energy recovery device needs no scheduled periodic maintenance. However, in the
event that disassembly is desired or required, the PX Q400 unit is designed so that it can be
assembled and disassembled in the field with only basic tools and equipment. These tools are
listed in Table 5-1. These tools, with the exception of the hoist and torque wrench, are included
in the PX Q400 tool kit (Energy Recovery Part Number 20469-01). In addition, the PX Q400 unit
can be mounted on a stand or on blocks to facilitate service, or the LP connection port can be
unthreaded in order to support the unit on the housing.

Energy Recovery Document Number 80882-01-00 15

 PX Q400 Energy Recovery Device

Table 5-1: Tool Kit 20469-01 bill of materials

Part Number Description Purpose
Tool designed to facilitate removal of Head Assembly.
20471-01 KIT, TOOL, HEAD PULLER, 9"
Glycerin included to lubricate O-rings.
10608-01 TOOL, REMOVAL, INTERCONNECT, 3" Tool to remove Interconnects.
Tool to reduce O-ring damage during install or removal
43684-01 TOOL, INSTALLATION, O-RING, 9" SIDE PORT
of Cartridge.
30207-01 TOOL, LIFTING STRAP, FABRIC Attached to the housing to support lifting purposes.
Lifting Eye for cartridge. To be used in conjunction with
10506-01 NUT, LIFTING EYE, 5/8"-11, 316 All Thread found in 20471-01 and Coupling Nut 30092-
01.
30092-01 NUT, COUPLING, 1/2"-13, TO, 5/8"-11, RED Couples All Thread found in 20471-01 with Cartridge.
30100-01 ROD, SPINNING, ROTOR Rod to help spin the rotor during assembly.
Tool to remove socket head cap screws from head
10130-01 WRENCH, ALLEN, TEE, 1/4"
assembly.
10137-01 WRENCH, COMBO, 3/4", CARBON STEEL Tool for Hex Bolts.
ANTI-SEIZE, .25 OZ, TUBE, NICKEL, MSDS Anti-Seize for threaded connections.
10225-01
REQUIRED
10327-01 WRENCH, STRAP, 3/4" MIN, 6-5/16" MAX Tool designed to install and remove LP connection ports.
10329-01 WRENCH, CRESCENT, 6" Tool for Hex bolts.
10085-01 NUT, LIFTING EYE, 1/2"-13, 316 Lifting Eye for cartridge

Replacement seals and alignment pins are included in Energy Recovery’s standard spare parts
kits (Energy Recovery Part Number 20467-01). One spare parts kit should be used each time a
PX unit is opened for service.

Replacements for other components in the PX assembly are available. Refer to assembly
drawing for PX component descriptions, part numbers, and the bill of materials.

Disassembly Procedure

Metal objects can chip or crack ceramic. Use caution when handling ceramic
CAUTION components to avoid damage.

Energy Recovery Document Number 80882-01-00 16

 PX Q400 Energy Recovery Device

Disassembly Procedure for the PX Device on the Rack or Piping

1. Depressurize all high-pressure and low-pressure piping to and from the PX unit.
2. Close all valves to and from the PX unit/rack or drain system.
3. Disconnect and remove the low-pressure piping from the upward facing end of the unit.
See Figure 5-2 as reference.
4. If more access is required, the PX can be removed from the rack.
a. Remove the all HP and LP couplings from the PX.
b. Remove the all HP and LP pipes connected to the PX.
c. Install sling around the PX as described in Section 3.2.
d. Remove the Saddle and Strap from the PX.
e. Remove the PX from the rack following the procedure listed in Section 3.2.
i. Bottom LP port may need to be removed if access is needed. Refer to
Section 5.2.2 Step 1.
5. Proceed with disassembly as directed in Section 5.2.2.

Figure 5-1: PX device on array rack Figure 5-2: LP port removed on array rack

Energy Recovery Document Number 80882-01-00 17

 PX Q400 Energy Recovery Device

PX Disassembly

1. Unscrew and remove the bottom LP port Figure 5-3. Otherwise, use blocks or a stand to
support the unit by the bottom end of the fiberglass housing shown in Figure 5-4. Do not
support the unit or apply stress to the low-pressure port.

Typical Dimensions shown in Inches [mm]

Figure 5-3: PX Q400 with Pipe Strap tool Figure 5-4: PX Support block shown as reference

2. Remove four (4) 5/16-inch socket-head cap screws, two (2) Securing Ring, and three (3)
Segmented Lock Ring from the top of the PX unit using a 1/4-inch Allen wrench as shown
in Figure 5-5.
a. Tip: Segmented Lock Ring maybe compressed due to pressurization of the PX. In
this instance, gently tap on the Bearing Plate with a plastic or wooden rod to loosen
the Head Assembly.

Energy Recovery Document Number 80882-01-00 18

 PX Q400 Energy Recovery Device

(4) 5/16-inch socket-head screw

(2) Securing Ring

(3) Segmented Lock Ring

Bearing Plate

Figure 5-5: Disassembly of PX Segmented and Securing Rings

3. Extract Head Assembly from the housing using an Energy Recovery Head Puller tool
20471-01 shown in Figure 5-6. Assisted lifting can be achieved using the All-thread and
Lifting Eye 5/8-11” as shown in Figure 5-7. Take care not to apply stress to the LP port if
it is still in place. Always use a wood block to protect the edge of the housing if force is
necessary to remove the head assembly.
a. Estimated weight of the Head Assembly is 25 lbs (11.3 kgs).

Head Assembly - 25lbs All-thread located in Head

(11.3kg) Puller Tool 20471-01.
• LP Port
• Bearing Plate
• Seal Plate

Figure 5-6: Head puller tool, PN 20471-01 Figure 5-7: Assisted lifting of the Head Assembly

Energy Recovery Document Number 80882-01-00 19

 PX Q400 Energy Recovery Device

4. Remove the Interconnect using Interconnect removal tool 10608-01. See Figure 5-8.
a. Tip: If more access is needed, proceed with removing the cartridge before
removing the Interconnect. See Section 5.2.2 step 5 for cartridge removal.
Remove Interconnect
using 10608-01 tool

Figure 5-8: Interconnect removal

5. Extracting the ceramic Cartridge assembly:

a. Attach the lifting tool onto the end of the Tension Rod. See Figure 5-9.
b. Install O-Ring installation tool 43684-01 in the top HP Port. Ensure the slot on the
tool is oriented in line with the LP ports. See Figure 5-10.
i. Tip: Tool helps prevent O-rings on the cartridge from rolling and/or pinching
during assembly and disassembly.
c. Clean the inner diameter of housing to remove any salt build up or biofouling
present.
d. Lubricate the inside of the housing with a water-soluble lubricant such as glycerin
or nonabrasive liquid soap.
e. Extract the PX Cartridge to the housing. It may be necessary to apply downward
force to the edge of the housing while hoisting to get the ceramic rotor
subassembly to slide out of the housing. Always use a wood block to protect the
edge of the housing if force is necessary to remove the rotor subassembly. Be
careful not to hit the rotor subassembly.
6. Remove the remaining bottom two (2) Interconnects from the PX Cartridge.

Energy Recovery Document Number 80882-01-00 20

 PX Q400 Energy Recovery Device

Lifting tool
• Lifting Eye 10506-01
• All thread 10606-01
• Coupling Nut 30092-01

Estimated Cartridge Weight:

50 lbs (22.8 kgs)
Figure 5-9: PX Cartridge lifting tool assembly. Can be installed with or
without Interconnects assembled.

O-ring
installation tool
43684-01

Ensure that the slot

on the O-ring
installation tool is in
line with the LP ports
of the PX.

Figure 5-10: Insert O-ring installation tool location and orientation

Energy Recovery Document Number 80882-01-00 21

 PX Q400 Energy Recovery Device

7. Support PX Cartridge and allow room for Tension Rod and wrench. Refer to Figure 5-11
for PX Cartridge construction and Figure 5-12 for reference support dimensions.
a. Note: Concentrate and Feedwater orientation is dependent on orientation of PX
during disassembly.

Tension Rod

Hex nut and Washers

Feedwater Endcover

Rotor-Sleeve Assembly

Concentrate Endcover

Figure 5-11: PX Cartridge construction Figure 5-12: Cartridge reference support dimensions

8. Follow these steps to disassemble the ceramic Cartridge:

a. Remove two (2) hex nut and two (2) washers from the top end of the tension rod.
b. Remove top two (2) Interconnect, two (2) Spacer, two (2) Pins, and Endcover as
shown in Figure 5-13.
i. Note: Be sure not to lose Pins during disassembly. Replace if required.

Energy Recovery Document Number 80882-01-00 22

 PX Q400 Energy Recovery Device

9. Lift the Rotor-Sleeve off the bottom Endcover as shown in Figure 5-14.
i. Note: Be sure to keep the Rotor from coming out of the sleeve.
a. If the rotor comes out of the sleeve, the following procedure should be applied:
i. Clean the rotor and sleeve. Rinse liberally with water.
ii. Inspect rotor and sleeve. Remove all debris. Avoid getting lint or dirt onto
the ceramic. Re-rinse if necessary.
iii. Identify the end of the rotor marked “CHK”. Place the rotor on a flat clean
surface with the end marked “CHK” oriented upward.
iv. Identify the end of the sleeve marked “CHK” and orient it upward. If the
sleeve is marked “CHK SWP” orient the "CHK SWP" end downward.
v. Hold the sleeve over the rotor. Slowly slide the sleeve onto the rotor. This is
a very tight fit and requires a gentle touch. Do not force the sleeve on by
pressing or hitting it. The sleeve should slide on easily. If the rotor and sleeve
become bound, use hot water on the sleeve to loosen it from the rotor.
vi. Contact Energy Recovery, Inc. if problems are encountered.

Figure 5-13: Disassembly of Spacer and Endcover Figure 5-14: Rotor-Sleeve removal

Thoroughly flush all PX components with clean water before assembling PX

CAUTION unit. Foreign material may inhibit rotor movement.

Energy Recovery Document Number 80882-01-00 23

 PX Q400 Energy Recovery Device

Assembly Procedure

This assembly procedure assumes that the PX Q400 unit has been disassembled per the previous
section. All parts should be carefully cleaned with clear water prior to assembly to ensure that
no dirt or debris contaminates the PX device. All parts should be thoroughly inspected for
damage and/or debris prior to reassembly. O-rings should be replaced with a new set. Do not
attempt to reassemble a PX unit with damaged or broken parts.

Improper lubrication.
Excess lubricant shown.

Proper Lubrication

Figure 5-17: O-ring lubrication

For best results, pre-lubricate all new O-rings with a very thin coating of Dow Corning 111 Valve
Lubricant and Sealant prior to installation. Wipe off any excess lubricant using a lint free cloth.
O-rings should appear wet but not feel sticky or have any excess lubricant on the surface. See
Figure 5-17. Dirt and debris can stick to pre-lubricated O-rings. Use appropriate precautions to
keep them clean during handling and storage.

Always lubricate all O-ring mating surfaces immediately prior to assembly with a suitable water-
soluble lubricant such as glycerin or liquid soap.

Cartridge Assembly

1. Install two (2) Interconnect Spacer shown in Figure 5-18.

a. Tip: Apply a small amount of glycerin to the outer diameter of the Interconnect
Spacer to help keep in place.
2. Replace two (2) O-rings Tension-rod.
3. Lubricate the Tension-rod O-rings and the inside of the center hole of both Endcovers.
4. Insert the Tension-rod through the ceramic Endcover.

Energy Recovery Document Number 80882-01-00 24

 PX Q400 Energy Recovery Device

5. Place Endcover and Tension-rod onto support block as shown in Figure 5-19.
a. Tip: Placing a block under the Tension-rod will prevent it from falling down.
(3) Dowel Pin

(2) Interconnect Spacer

(2) Dowel Pin

Figure 5-18: Interconnect Spacer install Figure 5-19: Dowel Pin install on Endcover

6. Insert three (3) Dowel Pins into the three (3) holes on the face of the Endcover as shown
in Figure 5-19. Make sure the Dowel Pins are fully seated in the Endcover and the sharp
ceramic edge has not created a burr. If a pin binds, remove and clear the pin and hole of
any debris.
7. Carefully place the assembled Rotor-Sleeve onto the Endcover. Make sure that the Dowel
Pins in the Endcover line up with the three (3) holes in the Sleeve as shown in Figure 5-
20.
8. Install two (2) washers and one (1) hex nut finger tight. The fiberglass washer should be
against the ceramic followed by the metal washer and then the hex nut as shown in Figure
5-21.

Energy Recovery Document Number 80882-01-00 25

 PX Q400 Energy Recovery Device

Hex Nut
Metal Washer
Fiberglass Washer

Figure 5-20: Rotor-Sleeve assembly Figure 5-21: Top Endcover and Cartridge hardware

9. Carefully inspect the contact lines between the sleeve and the Endcovers to be sure there
are no gaps, see Figure 5-22. If a gap is present, disassemble and clean to ensure no debris
is in the cartridge.
a. Tip: Debris can often be trapped in the circumferential groove on the Endcover and
in the Dowel Pin counter-bore.

Inspect contact line to

ensure no gaps are present.

Figure 5-22: Inspect contact line between Endcover and Sleeve

Energy Recovery Document Number 80882-01-00 26

 PX Q400 Energy Recovery Device

10. Torque Sequence. Refer to Figure 5-23.

a. Tighten the nut closest to the cartridge assembly and torque to 15 ft-lb (20 N-m).
b. Thread the second nut onto the tension rod. This nut will act as a lock nut. Torque
to 40 ft-lb (56 N-m) while holding the adjacent nut.
c. Torque the 2nd nut on the opposite side to 40 ft-lb (56 N-m) while holding the
adjacent nut.

2nd- Torque nut to 40 ft-lb (56 N-m)

1st- Torque nut to 15 ft-lb (20 N-m)

3rd- Torque nut to 40 ft-lb (56 N-m)

Figure 5-23: Cartridge torque specification and sequence

11. Verify that the both inner nut (closest to the Endcovers), both are secured.
12. Verify that the rotor can spin freely. Use a wooden or plastic dowel to advance rotor as
illustrated in Figure 5-24.

DANGER DO NOT SPIN ROTOR WITH FINGER. Spinning Rotor can cause harm.

½” Diameter dowel shown as reference

Figure 5-24: Verify the Rotor spins freely

Energy Recovery Document Number 80882-01-00 27

 PX Q400 Energy Recovery Device

13. Lubricate the Cartridge O-rings, the four (4) LP Interconnect

counter-bore and the inside of the housing.
a. Tip: Inspect O-ring on Cartridge to ensure no tears,
rips, or any other defects. Replace O-rings if required.
14. Install the 2nd set of Dowel Pins and Interconnect Spacers.
Refer to Figure 5-16.
15. Attach the lifting eye to the Cartridge assembly. Refer to
Figure 5-9.
16. Lubricate eight (8) Quad rings on Interconnect.
a. Tip: Inspect Quad ring to ensure no tears, rips, or any
other defects. Replace Quad ring if required.
17. Install Interconnect into Endcover. Lift the Cartridge and
install bottom Interconnect shown in Figure 5-25.
18. Install O-ring Installation tool shown in Figure 5-10.
Figure 5-25: Cartridge assembly
19. Lift Cartridge assembly and lower into housing. Refer to with lifting tool
Figure 5-9.
a. Tip: Observe location of the Seal Plate interconnect counter-bore and orient the
Cartridge assembly accordingly. Temporarily marking the housing can help.
20. Lubricate O-ring on Seal Plate.
a. Tip: Inspect O-ring to ensure no tears, rips, or any other defects are present.
Replace O-ring if required.
21. Lift the Head Assembly and lower into housing. Follow reverse sequence as shown in
Figure 5-7. The Segmented Ring should slide into the housing groove if Cartridge and
Head Assembly are properly seated. If issues occur, remove head assembly and check
alignment between four (4) Interconnects and two (2) Seal Plates.
a. Tip: Observe location of the Endcover Interconnects and orient the Head Assembly
accordingly.
22. Install the three (3) Segmented Lock Ring, followed by two (2) Securing Ring, and fastened
with four (4) 5/16-inch socket head cap screws. See Figure 5-5.

Energy Recovery Document Number 80882-01-00 28

 PX Q400 Energy Recovery Device

23. If LP Port was removed, install following the procedure below. See Figure 5-26 for
reference.
a. Apply food grade anti-seize to LP port thread.
b. Lubricate O-ring.
i. Tip: Inspect O-ring for to ensure no tears, rips, or any other defects are
present. Replace O-ring if required.
c. Install O-ring into Seal Plate groove, highlighted green in Figure 5-26.
d. Thread LP Port into Bearing Plate by hand. Use strap wrench shown in Figure 5-3 if
necessary.

LP Port

LP Port male thread

O-Ring

O-ring groove located on Seal Plate

inner diameter (Highlighted in green)

Figure 5-26: Low pressure port installation

Energy Recovery Document Number 80882-01-00 29

 PX Q400 Energy Recovery Device

6. TROUBLESHOOTING

This section is designed to guide the operator in identifying and correcting most of the problems
that could occur in the PX energy recovery device. The instructions provided below are intended
for use by personnel with general training and experience in the operation and maintenance of
fluid handling systems. This is not intended as a comprehensive maintenance guide. Conditions
not covered in this section may be resolved by contacting Energy Recovery’s Service
Department.

Preliminary Procedures

• Always check for proper valve configuration for the operation mode selected.
• Always inspect and test equipment or apparatus for possible causes of malfunctions
before performing replacements.

Instrumentation

The following list of instrumentation is useful in monitoring and diagnosing the operation of PX
devices.
• Energy Recovery requires that one flowmeter be installed in the PX unit(s) HP flow circuit
and one in the LP flow path.
• Energy Recovery requires a pressure instrument be installed between the low-pressure
outlet and any control valve to monitor device backpressure.
• Energy Recovery recommends that high flow and pressure alarms/shutdowns be
incorporated into the system design to protect the PX unit(s) from potential damage by
high flows.
• Energy Recovery suggests using a TDS meter to check the conductivity of the streams
entering and exiting the PX device to monitor device performance.

When using this troubleshooting guide, please read all the probable causes before taking any
action. Use common sense and select the cause that seems to best fit the given situation.

Energy Recovery Document Number 80882-01-00 30

 PX Q400 Energy Recovery Device

Troubleshooting Guide

SYMPTOM PROBABLE CAUSE CORRECTIVE ACTION

1. Operating PX unit(s) above rated Immediately reduce flow rates.
flow rates To increase system capacity, add PX unit(s)
in parallel to existing units.
2. Operating PX unit(s) below Increase feedwater supply pressure. Re-
minimum back-pressure balance the system as described in Section
4.
3. Air in system Bleed air.

A. Excessive sound 4. PX unit or ceramic cartridge Verify that the PX unit has been installed
levels installed upside down with the end marked “HPIN” oriented
toward the concentrate inlet. If service
was performed, verify the orientation of
the ceramic cartridge by removing the
concentrate-side port bearing plate
assembly. The endcover marked
“Concentrate” should be oriented toward
the concentrate inlet/outlet.
5. Damaged ceramic Contact the Energy Recovery Service
Department
1. Membrane fouling or scaling Contact membrane manufacturer for
cleaning recommendations.
2. Excessively high recovery in the RO Reduce recovery by increasing and
system balancing flows through the PX unit(s). Do
not exceed recommended maximum PX
B. Excessive high unit flow rates.
pressure 3. HPP is operating at too high of a Adjust flow rates.
flow rate
4. Low pressure flow is less than Adjust flow rates. See Section 4.
high-pressure flow, resulting in
mixing and high RO feed water
salinity

Energy Recovery Document Number 80882-01-00 31

 PX Q400 Energy Recovery Device

5. Stuck rotor See Symptom D.

C. High salinity in 1. Unbalanced system Check flow rates. See Section 4.
high-pressure
2. A stalled rotor See Symptom D.
feedwater stream
1. Foreign debris or biological growth Conduct a fresh water flush.
lodged in device Disassemble PX device per manufacturer
procedure and remove foreign debris.
D. Stalled rotor - no If problem persists, contact the Energy
audible rotation Recovery Service Department.
2. Operating system above rated Check flow rates and pressures. See
pressure or below rated flow Section 1.5.
capacity
1. Membrane fouling or scaling Contact membrane manufacturer for
cleaning recommendations.
E. Low permeate flow 2. High pressure leak Identify and fix leak in RO system or inside
PX device.
3. HPP problem Contact HPP manufacturer or service HPP.

Energy Recovery Document Number 80882-01-00 32

 PX Q400 Energy Recovery Device

7. LEARNING MORE AND CONTACTING ENERGY RECOVERY

More information about PX technology is available on Energy Recovery’s website:

www.energyrecovery.com, by emailing Energy Recovery’s service department at
support@energyrecovery.com, or by telephoning Energy Recovery at +1-510-483-7370. Refer
to Technical documents for PX device component names and the bill of materials for the PX unit
assembly. Refer to Products section in Energy Recovery website for recommended spare parts
and tool kits.

Energy Recovery’s Technical Services staff offers commissioning service for all Energy Recovery
products during field installation and/or at a RO system manufacturer’s location. Service rate
quotes are available upon request.

8. REVISION LOG

Revision Description Date

00 Initial Release 1/17/23

Energy Recovery Document Number 80882-01-00 33