Experiment Instructions

HM 111 Pipe Networks

 HM 111 PIPE NETWORKS
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Experiment Instructions

Last modification by: Dipl.-Ing. Peter Mittasch

This manual must be kept by the unit.

Before operating the unit:

- Read this manual.
- All participants must be instructed on
handling of the unit and, where appropriate,
on the necessary safety precautions.

Version 0.2 Subject to technical alterations

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 HM 111 PIPE NETWORKS

Table of Contents

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1 Intended use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2 Structure of the safety instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.3 Safety instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.4 Ambient conditions for operation and storage location . . . . . . . . . . . . 5
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3 Unit description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1 Pipe sections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2 Pressure measuring points with annular measuring chambers. . . . . . 9
3.3 Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.4 Differential pressure measurement with 2-tube manometer . . . . . . . 11
3.4.1 Bleeding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.4.2 Setting the zero position . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.4.3 Measuring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.5 Measurement using the differential pressure manometer . . . . . . . . . 16
3.5.1 Bleeding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.6 Shutting down . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.7 Maintenance and care . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4 Fundamental principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.1 Flow through pipes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.2 Flow through pipe elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.2.1 Coefficients of resistance for special pipe elements . . . . . . . 20
4.2.2 Introduction of a constant K . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.2.3 Parallel and series connection of pipe elements with a flow
through them. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

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5 Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.1 Experiment 1: Calibration of pipe sections . . . . . . . . . . . . . . . . . . . . 23
5.1.1 Aim of experiment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.1.2 Preparing the experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.1.3 Performing the experiment . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.1.4 Measured values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
5.1.5 Evaluation of the experiment . . . . . . . . . . . . . . . . . . . . . . . . 31
5.2 Experiment 2: Determination of constants for bends. . . . . . . . . . . . . 35
5.2.1 Aim of experiment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
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5.2.2 Preparing the experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

5.2.3 Performing the experiment . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5.2.4 Measured values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
5.2.5 Evaluation of the experiment . . . . . . . . . . . . . . . . . . . . . . . . 40
5.2.6 Evaluation of experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

6 Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
6.1 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
6.2 List of key symbols and units used . . . . . . . . . . . . . . . . . . . . . . . . . . 48
6.3 Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
6.4 Pipe coefficient of friction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
6.5 Worksheets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
6.5.1 Formulae. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
6.5.2 Measured values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
6.5.3 Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
6.6 Pipe networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
6.7 Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
6.7.1 Calibration curve for 25mm pipe (pipe section A) . . . . . . . . . 57
6.7.2 Calibration curve for 20mm pipe (pipe section B). . . . . . . . . 58
6.7.3 Calibration curve for 16 mm pipe . . . . . . . . . . . . . . . . . . . . . 59
6.7.4 Calibration curve for bend. . . . . . . . . . . . . . . . . . . . . . . . . . . 60

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 HM 111 PIPE NETWORKS

1 Introduction

Determining the pressure and flow in more com-

plex pipe systems is a common problem in pipe
installation. The HM 111 Pipe Networks trainer
enables various types of pipe systems to be set
up and investigated. These can be assembled on
the top of the trainer using the pipe elements sup-
plied. The range of experiments stretches from
the investigation of single pipes to measurements
on complex pipework. In addition, the trainer con-
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tains a supply tank with pump as well as a further

measuring tank for the flow measurement. This
enables experiments to be performed in a closed
water circuit. For pressure measurements, a 2-
tube pressure gauge and a differential pressure
gauge with different measuring ranges are
included.
Installation on a mobile laboratory trolley makes
use in seminar rooms and training rooms easier.

1 Introduction 1
 HM 111 PIPE NETWORKS

Learning content
• Plotting a calibration curve for individual pipe
sections: Pressure loss against flow
• Parallel connection of pipe sections
• Series connection of pipe sections
• Combined series and parallel connection
• Investigation of a ring circuit
• Differential pressure measurement
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• Pressure losses at various pipe elements

1 Introduction 2
 HM 111 PIPE NETWORKS

2 Safety

2.1 Intended use

The unit is to be used only for teaching purposes.

2.2 Structure of the safety instructions

The signal words DANGER, WARNING or

CAUTION indicate the probability and potential
severity of injury.
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An additional symbol indicates the nature of the

hazard or a required action.

Signal word Explanation

Indicates a situation which, if not avoided, will result in

DANGER death or serious injury.

Indicates a situation which, if not avoided, may result in

WARNING death or serious injury.

Indicates a situation which, if not avoided, may result in

CAUTION minor or moderately serious injury.

Indicates a situation which may result in damage to

NOTICE equipment, or provides instructions on operation of
the equipment.

2 Safety 3
 HM 111 PIPE NETWORKS

Symbol Explanation

Electrical voltage

Notice

2.3 Safety instructions

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WARNING
Electrical connections are exposed when the
control cabinet is open.
Danger of electric shock.
• Before opening the control cabinet: Disconnect
the mains plug.
• Work should only be carried out by qualified
electricians.
• Protect the control cabinet against moisture.

NOTICE
The submersible pump is destroyed if operated
without water.
• When operating the submersible pump: Ensure
that the supply tank is filled.

2 Safety 4
 HM 111 PIPE NETWORKS

NOTICE
Frost damage is possible when the system is
stored.
• Only store the system in a frost-free location.
• If there is a risk of frost, drain using the drain
valve.
• If the unit will not be used for a long period,
drain the water.
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NOTICE
Damage possible due to leaks.
• When changing pipe elements in the pipe sec-
tions, ensure that no sealing rings become
detached and fall off.
• Prior to commissioning the pump, check all
connections for leaks.

2.4 Ambient conditions for operation and storage location

• Enclosed space.
• Free of dirt and moisture.
• Even and stable surface.
• Frost-free.

2 Safety 5
 HM 111 PIPE NETWORKS

3 Unit description

8 7 3 6 5 4 3 2 1
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View of storage
panel, see Fig.
3.2, Page 7

9 10 11 12

1 Two-tube manometer
2 Measuring tank
3 Annular measuring chamber
4 Frame for experiment fittings
5 Differential pressure gauge
6 Pipe sections
7 Control cabinet
Submersible pump (13) 8 Feed valve
(Supply tank (9) shown
as transparent) 9 Supply tank
10 Main valve for flow adjustment
11 Scale for reading the water level
12 Gate valve for draining the measuring tank
13 Submersible pump

Fig. 3.1 HM 111 unit layout

3 Unit description 6
 HM 111 PIPE NETWORKS

Connection

Connection 180°

Connection 180°
with outlet

Outlet
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3-way connection

3-way connection
with outlet
Fig. 3.2 Storage panel for pipe elements

The entire experimental setup is fitted on a mobile

laboratory trolley. The trolley also contains the
water supply for the experiments. This consists of
a supply tank (9), from which a submersible pump
(13) pumps water to the pipe sections to be inves-
tigated (6). The pump is turned on at the control
cabinet (7) and the required flow is set using a
main valve (10). Five pipe sections are pre-
assembled on a removable frame (4) and can be
extended to create a pipe network using the pipe
elements supplied. On the frame there are five
permanently installed feed valves (8) for precise
regulation of the flow. The pressure loss is meas-
ured whilst there is a flow through the pipe sec-
tions. A differential pressure gauge (5) is available

3 Unit description 7
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for pressure losses greater than 100mbar, or a

2-tube manometer (1) for losses less than 100
mbar. Once the water has flowed out of the pipe
sections into the measuring tank (2), the scale
(11) and a stopwatch can be used to determine
the flow. The connection between the measuring
tank and the supply tank can be shut off using a
gate valve (12) for volumetric flow measurements.
The pipe elements required to connect individual
pipes to form a pipe network are located on a stor-
age panel (see Fig. 3.2, Page 7) on the side of the
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trolley.

3.1 Pipe sections

A 25mm x 1,9mm
B 20mm x 1,5mm
C 16mm x 1,8mm
Fig. 3.3 Pipe network
(Shown here: "Calibration of pipe sections" pipe network)

3 Unit description 8
 HM 111 PIPE NETWORKS

3.2 Pressure measuring points with annular measuring chambers

The pressures are measured on the pipe using

annular chambers. The annular chambers are
designed in such a way that there is no - or only
minimal - restriction of the cross-section and the
flow can pass the measuring point unimpeded.

Fig. 3.4 View of an annular measuring

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chamber with self-closing

rapid action hose coupling

Fig. 3.5 Section through an annular

measuring chamber. The filled
annular measuring chambers
are shown in blue.

3 Unit description 9
 HM 111 PIPE NETWORKS

3.3 Commissioning

The following steps are to be performed for com-

missioning of the unit:
1. Set up the trainer on an even surface.
2. Fill the supply tank with water to around 5cm
below the top edge.

NOTICE
Risk of damage to the unit.
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• Before connecting to the electrical supply:

Make sure that the laboratory power supply
corresponds to the specifications on the unit's
rating plate.

3. Connect the power supply.

4. Extend the pipes on the frame to create a pipe
network. The frame can be detached to do this.
Measuring tank 5. Place the pipe network on the top of the trainer
in such a way that the outflow of water is flow-
ing into the measuring tank (see Fig. 3.6).
Fig. 3.6 6. Connect the supply line for the water circuit to
Pipe network connection
the pipe network using the hose (see Fig. 3.7).
– Install a sealing ring between the hose and
the pipe network water connection.

Fig. 3.7 Rear view

3 Unit description 10
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7. Turn the pump on with the main valve closed by

setting the main switch to "ON" and pressing
the pump switch (Fig. 3.8).
8. Set the required flow using the main valve and
the supply valve.

Main switch Pump switch

Fig. 3.8 Control cabinet

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3.4 Differential pressure measurement with 2-tube manometer

The two-tube manometer allows measurement of

both differential pressures and excess pressures
Bleed valve
in mm water column, and the latter can then be
converted into absolute pressures based on the
atmospheric air pressure.
• The measuring range is a 0...1000mm water
column.
Water column
• The manometer comprises two glass level
tubes with a metal mm scale behind them.
• The two level tubes are connected together at
the top and have a shared bleed valve.
• Differential pressure is measured with the
bleed valve closed and excess pressure with
the bleed valve open.
• The measuring points are connected to the
lower ends of the level tubes using rapid action
Rapid action hose couplings.
coupling
• Each level tube has a drain valve at the lower
Drain valve
end.
Fig. 3.9 Two-tube manometer

3 Unit description 11
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Above the water columns shown in Fig. 3.10 there

Air cushion
is an air cushion that can have any air pressure.
The differential pressure required is given by
h
h1

h2 p = h    g (3.1)

p1 p2 1 mbar
p  h  ------ -------------- (3.2)
10 mm
Fig. 3.10
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where
h in mm

To set up the manometers (bleed, adjust level) it

is recommended that a single pipe section with
two pressure measuring connections is used first.

3 Unit description 12
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3.4.1 Bleeding

As air bubbles in the measuring hoses cause

incorrect measurements due to the low density of
the air, the hoses must be bled.
• Set up the hose connections from the measur-
ing connections on the pipe section to be inves-
tigated to the connections on the manometer,
enduring that the valves on the manometer are
closed.
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• Turn on the pump and set up a flow in the pipe

section (using the main valve and supply
valve).
• Open the two lower outlet valves and the sup-
ply lines to the manometer are bled by a water
flow.
Fig. 3.11 Bleeding
• After bleeding the lines, close the lower outlet
valves simultaneously.

3 Unit description 13
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3.4.2 Setting the zero position

To obtain the largest possible measuring range,

the level should be located in the centre of the
scale after adjustment. One possible procedure
is:
• Set up a flow in the pipe section. Pressure is
present at the connections on the manometer,
creating a height difference between the two
water columns on the manometer.
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• By briefly opening the upper bleed valve it is

now possible to adjust the (different height)
water columns to the required area of the
scale.
• After closing the supply valve on the pipe sec-
Fig. 3.12 Setting the zero position tion, the two water columns must settle to the
same level, as shown in Fig. 3.12. This shows
that the manometer is correctly adjusted for the
measurements.

NOTICE
The water columns can only be adjusted upwards
using the bleed valve.

3 Unit description 14
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3.4.3 Measuring

After bleeding, the measurement can be started.

This is done by setting the required flow on the
pipe section. The differential pressure p that is
produced between the two measuring points is
read directly as the head loss hloss on the two
water columns. If the differential pressure to be
hloss
measured exceeds the measuring range of the
two-tube manometer, the differential pressure
manometer is used instead. After performing the
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experiment, the manometer can be depressurised

by opening the bleed valve and the two outlet
valves. This drains the water.

Fig. 3.13 Differential pressure display

3 Unit description 15
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3.5 Measurement using the differential pressure manometer

3.5.1 Bleeding

As air bubbles in the measuring hoses cause

incorrect measurements due to the low density of
the air, the hoses must be bled.
• Connect the hoses to the measuring connec-
tions on the pipe section to be investigated.
• Turn on the pump and set up a flow in the pipe
section (using the main valve and supply
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valve).
• Using an object (screwdriver or Allen key)
press on the pin for the rapid action coupling on
the other end of the hose.
– The self-closing valve opens and water
flows out.
– Bleed the valves.
• Pull the ring of the rapid action coupling back
again.
– The self-closing valve closes.
• Connect the rapid action couplings on the dif-
ferential pressure manometer.

3 Unit description 16
 HM 111 PIPE NETWORKS

3.6 Shutting down

1. Turn off the pump.

2. Turn off the trainer using the main switch.
3. Disconnect the trainer from the mains electric-
ity.
4. Drain the tank using the drain valve (see Fig.
3.14).
5. Drain the two-tube manometer.
To do this, open the outlet valves.
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6. Detach the hoses and drain them. (Press an

object (screwdriver or Allen key) on the pin for
the rapid action coupling. The self-closing
Drain valve
valves open and the water can flow out of the
hose.)
Fig. 3.14 Drain valve
7. Store the sealing rings separately.

3.7 Maintenance and care

The use of corrosion resistant materials means

that the trainer is maintenance-free. We recom-
mend adding an agent to the water in the supply
tank to inhibit algae growth. If the trainer will not
be used for an extended period, the water should
be drained.

3 Unit description 17
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4 Fundamental principles

The basic principles set out in the following make

no claim to completeness. For further theoretical
explanations, refer to the specialist literature.

The experiments are designed to investigate the

pressure loss ploss and the head loss hloss when
water flows through different pipe networks. In
addition to the various pressure differences that
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occur in a flow through a pipe network, straight

pipe sections and pipe sections with 1 or 2 bends
can be investigated.

4.1 Flow through pipes

The pressure loss ploss that occurs in a flow

through pipes is caused by the friction of the flow-
ing fluid on the wall of the pipe.
The pressure loss is proportional
• to the length l of the pipe
• to the pipe coefficient of friction 
• to the density  of the fluid
• to the square of the flow velocity v.

4 Fundamental principles 18
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In addition, the pressure loss increases as the

pipe diameter d is reduced.
The pressure loss is calculated as follows:

l 2
p loss = -----------    v (4.1)
2d

The associated head loss hloss is calculated as

follows
2
l v
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h loss = ---------  ----------- (4.2)

d 2g

In the case of turbulent pipe flow (Re > 2320) the

pipe coefficient of friction  depends on the pipe
roughness k and the Reynolds number Re. The
pipe roughness k defines the height of projections
on the wall in mm. The roughness of the pipes
used in the experiments is listed in the appendix
in Chapter 6.1, Page 46. The relationship
between Re,  and k is shown in the Colebrook
and Nikuradse diagram (see Fig. 6.1, Page 51).
This relates the wall roughness k to the pipe diam-
eter d.

The Reynolds number Re is calculated from the

pipe diameter d, the flow velocity v and the kine-
matic viscosity  .

vd
Re = ---------- (4.3)


The kinematic viscosity  of water depending on

temperature can be found in the table in
Chapter 6.3, Page 49.

4 Fundamental principles 19
 HM 111 PIPE NETWORKS

The flow velocity v is calculated from the flow

and the pipe cross-section.

4Q
v = ------------- (4.4)
2
d
For hydraulically smooth pipes (Re < 65 d/k)
and with a Reynolds number in the range
2320 < Re < 105 the pipe coefficient of friction is
calculated using the Blasius formula

 = 0,3164
------------------ (4.5)
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4 Re

Experience has shown that with an unknown  ,

good results can be obtained using an assumed
value  = 0,02.

4.2 Flow through pipe elements

4.2.1 Coefficients of resistance for special pipe elements

Special pipe components and fittings such as pipe

bends, pipe branches, changes in cross-section
or also valves and flaps produce additional pres-
sure losses apart from the wall friction losses.
Apart from a few special cases, unlike the wall
friction losses investigated in the previous section
the additional pressure losses cannot be calcu-
lated directly.

4 Fundamental principles 20
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4.2.2 Introduction of a constant K

To make the investigations on the pipe networks

as clear as possible, a constant K is introduced to
represent the combined resistances in the meas-
ured section:

p-
K = ------ (4.6)
2
Q

The value of Q should be stated in m3/h and the

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value of p in mbar.

4.2.3 Parallel and series connection of pipe elements with a flow through
them

Parallel and series connections of pipes and pipe

elements behave in a similar way to electric cur-
rent. In electrical engineering, with series connec-
tion the resistances are added together, whilst in
the case of parallel connection the reciprocals
must be added together:

K 1 + K 2 + K 3 + ... (4.7)

1 + ------------
------------ 1 + ------------
1 + ... (4.8)
K1 K2 K3

The pressure losses caused by the flow resist-

ances in the pipe sections behave in exactly the
same way. For example, if there is a pipe section
with 2 pipe bends between 2 pressure measuring
points, the total losses read on the manometer are
made up of 3 components:

K total = K bend + K pipe + K bend (4.9)

4 Fundamental principles 21
 HM 111 PIPE NETWORKS

For parallel connections, the individual compo-

nents of the measured resistances must be calcu-
lated as set out in Formula (4.8), Page 21, e.g.:

1 - = ---------------------
------------------- 1 - + ---------------------
1 - + ... (4.10)
K total K pipe1 K pipe2
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4 Fundamental principles 22
 HM 111 PIPE NETWORKS

5 Experiments

The selection of experiments makes no claims of

completeness but is intended to be used as a
stimulus for your own experiments.
The results shown are intended as a guide only.
Depending on the construction of the individual
components, experimental skills and environmen-
tal conditions, deviations may occur in the experi-
ments. Nevertheless, the laws can be clearly
demonstrated.
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5.1 Experiment 1: Calibration of pipe sections

5.1.1 Aim of experiment

In the "Calibration of pipe sections" pipe network

(Chapter 6.6, Page 56), the relevant pressure
loss is to be used to determine the constant K for
the pipe sections.

5 Experiments 23
 HM 111 PIPE NETWORKS

5.1.2 Preparing the experiment

Pipe network water connection

Pipe element Pipe element
connection outlet

25mm x 1,9mm Pipe section 1

20mm x 1,5mm
Pipe section 2

20mm x 1,5mm
All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

16mm x 1,8mm
Pipe section 3

16mm x 1,8mm

890
Supply valves
Fig. 5.1 "Calibration of pipe sections" pipe network

1. Fit the "Calibration of pipe sections" pipe net-

work on the frame as shown in Fig. 5.1.
– Install sealing rings between the pipe ele-
ment and the pipe section.
2. Place the frame on the trainer.
3. Connect the hose to the water connection for
the pipe network.
– Install a sealing ring between the hose and
the water connection for the pipe section.
4. Close the supply valves for the pipe network.
5. Close the main valve.
6. Turn on the pump.

5 Experiments 24
 HM 111 PIPE NETWORKS

The experimental setup is now ready for use.

5.1.3 Performing the experiment

Supply valves

Pipe section 1
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Pipe section 2

Pipe section 3

Pressure measuring connection Pressure measuring connection

Fig. 5.2 "Calibration of pipe sections" pipe network

7. Open the main valve.

8. Open the supply valve for the pipe section 1 to
create a flow through the pipe section.
If measuring using the 2-tube manometer:
9. Connect the pressure measuring connections
on the pipe section with a flow through it to the
2-tube manometer using hoses.
10. Bleed the hoses as described in
Chapter 3.4.1, Page 13.

5 Experiments 25
 HM 111 PIPE NETWORKS

11. If necessary, adjust the manometer for the

measurement as described in Chapter 3.4.2,
Page 14.
Continue with step 14.

If measuring using the differential pressure

manometer:
12. Bleed the hoses as described in
Chapter 3.5.1, Page 16.
All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

13. Connect the pressure measuring connections

on the pipe section with a flow through it to the
differential pressure manometer using the
hoses.

14. Note the following:

– Differential pressure or head loss
– Time elapsed for filling the measuring tank
with 10 L of water.
15. Close the supply valve for pipe section 1.
16. Open the supply valve for pipe section 2.
17. Repeat steps 9 to 14.
18. Close the supply valve for pipe section 2.
19. Open the supply valve for pipe section 3.
20. Repeat steps 9 to 14.
21. Close the supply valve for pipe section 3.
22. Repeat steps 8 to 21 with the same main
valve setting so that all measurements have
been performed a total of three times.

5 Experiments 26
 HM 111 PIPE NETWORKS

23. Change the flow using the main valve.

24. Repeat steps 8 to 23 until you have measured
at least five different flows three times for each
pipe section.
25. Turn off the pump.
All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

5 Experiments 27
 All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

Experiment: Calibration of pipe sections

5.1.4
Date: 08.04.2015
HM 111
Name: Mittasch

5 Experiments
Pipe section / pipe element(s): "Calibration of pipe sections" pipe network
Pipe section 1

1st iteration 2nd iteration 3rd iteration

hloss ploss hloss ploss hloss ploss

Measure-
V in L t in s in mm in V in L t in s in mm in V in L t in s in mm in
ment
WC bar WC bar WC bar
Measured values

1 10 11,08 852-298 0,0554 10 11,16 852-298 0,0554 10 11,01 850-296 0,0554

PIPE NETWORKS

2 10 12,47 760-345 0,0415 10 12,92 758-347 0,0411 10 12,59 762-344 0,0418

3 10 15,00 685-383 0,0302 10 15,24 686-382 0,0304 10 14,89 685-383 0,0302

4 10 19,47 418-612 0,0194 10 19,71 612-418 0,0194 10 19,47 610-420 0,0190

5 10 35,98 522-463 0,0059 10 35,52 522-463 0,0059 10 35,88 522-464 0,0058

28
 All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

Experiment: Calibration of pipe sections

Date: 08.04.2015
HM 111
Name: Mittasch

5 Experiments
Pipe section / pipe element(s): "Calibration of pipe sections" pipe network
Pipe section 2

1st iteration 2nd iteration 3rd iteration

hloss ploss hloss ploss hloss ploss

Measure-
V in L t in s in mm in V in L t in s in mm in V in L t in s in mm in
ment
WC bar WC bar WC bar

1 10 12,40 0,1200 10 12,53 0,1300 10 12,56 0,1200

PIPE NETWORKS

2 10 14,13 0,0950 10 13,30 0,0900 10 14,00 0,0950

3 10 16,11 948-128 0,0820 10 16,05 948-127 0,0821 10 16,35 948-128 0,0820

4 10 20,18 791-252 0,0539 10 20,04 790-251 0,0539 10 20,17 788-250 0,0538

5 10 36,65 580-410 0,0170 10 36,97 579-412 0,0167 10 37,00 580-410 0,0170

29
 All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

Experiment: Calibration of pipe sections

Date: 08.04.2015
HM 111
Name: Mittasch

5 Experiments
Pipe section / pipe element(s): "Calibration of pipe sections" pipe network
Pipe section 3

1st iteration 2nd iteration 3rd iteration

hloss ploss hloss ploss hloss ploss

Measure-
V in L t in s in mm in V in L t in s in mm in V in L t in s in mm in
ment
WC bar WC bar WC bar

1 10 17,17 0,4000 10 17,31 0,4000 10 17,12 0,4000

PIPE NETWORKS

2 10 17,14 0,3500 10 18,79 0,3500 10 18,83 0,3600

3 10 19,65 0,3000 10 20,08 0,3100 10 19,84 0,3100

4 10 23,53 0,2000 10 22,81 0,2100 10 23,41 0,2100

5 10 39,32 861-150 0,0711 10 39,19 858-148 0,0710 10 38,88 859-148 0,0711

30
 HM 111 PIPE NETWORKS

5.1.5 Evaluation of the experiment

The measured values recorded enable a "pres-

sure loss against flow" calibration curve to be pro-
duced for each of the pipes investigated.
The calibration curves are shown in the appendix
to the instructions. The measured values that pro-
vide the basis for the calibration curves have also
been used to calculate the constant K using
Formula (4.6), Page 21, using the flow in the unit
m3/h:
All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

For example, for pipe section 1 at the highest flow:

p loss 55,4mbar-
K = -----------
- = ----------------------------
2 3 2
Q 3,18 m ------- 
 h 

2 2
 h - = 5,48 mbar  h-
= 55,4mbar
------------------------------------ ------------------------
6
2 6
3,18 m m

All measurements have been carried out a total of

three times.
Calculate the arithmetic mean for V, t and ploss.
Example for tm:

t1 + t2 + t3
t m = --------------------------
- (5.1)
3

5 Experiments 31
 All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

Experiment: Calibration of pipe sections

Date: 08.04.2015
HM 111
Name: Mittasch

5 Experiments
Pipe section / pipe element(s): "Calibration of pipe sections" pipe network
Pipe section 1

p calc in
Measure- K in mbar Variation in
ploss,m in 3 2
Vm in L tm in s Q in L/s Q in m /h mbar  h
ment mbar ----------------------- where mbar
6
m K = 5,5

1 10 11,32 55,4 0,8834 3,18 5,48 55,6 0,2

PIPE NETWORKS

2 10 12,66 41,5 0,7899 2,84 5,15 44,4 2,9

3 10 15,04 30,3 0,6649 2,39 5,30 31,4 1,1

4 10 19,64 19,3 0,5092 1,83 5,76 18,4 -0,9

5 10 35,79 5,9 0,2794 1,01 5,78 5,6 -0,3

Kpipe1 = 5,5

32
 All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

Experiment: Calibration of pipe sections

Date: 08.04.2015
HM 111
Name: Mittasch

5 Experiments
Pipe section / pipe element(s): "Calibration of pipe sections" pipe network
Pipe section 2

p calc in
Measure- K in mbar Variation in
ploss,m in 2
Vm in L tm in s Q in L/s Q in m3/h mbar
ment mbar ---------------------- where mbar
 h-
6
m K = 15

1 10 12,50 123,0 0,8000 2,88 14,83 124,4 1,4

PIPE NETWORKS

2 10 13,81 93,0 0,7241 2,61 13,65 102,2 9,2

3 10 16,17 82,0 0,6184 2,23 16,49 74,6 -7,4

4 10 20,13 53,9 0,4968 1,79 16,82 48,1 -5,8

5 10 36,78 16,9 0,2712 0,98 17,60 14,4 -2,5

Kpipe2 = 15

33
 All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

Experiment: Calibration of pipe sections

Date: 08.04.2015
HM 111
Name: Mittasch

5 Experiments
Pipe section / pipe element(s): "Calibration of pipe sections" pipe network
Pipe section 3

K in p calc in
Measure- ploss,m in 2 Variation in
Vm in L tm in s Q in L/s Q in m3/h mbar  h mbar
ment mbar ----------------------
- mbar
6 K = 90
m

1 10 17,20 400,0 0,5814 2,09 91,57 400,0 0

PIPE NETWORKS

2 10 18,59 353,0 0,5379 1,94 93,79 383,7 -14,3

3 10 19,86 307,0 0,5035 1,81 93,71 294,9 -12,1

4 10 23,25 207,0 0,4301 1,55 86,16 216,2 9,2

5 10 39,13 71,7 0,2556 0,92 84,71 76,2 4,5

Kpipe3 = 90

34
 HM 111 PIPE NETWORKS

5.2 Experiment 2: Determination of constants for bends

5.2.1 Aim of experiment

On the "Series connection" pipe network

(Chapter 6.6, Page 56), the total pressure loss is
to be used to determine the constant K for a pipe
bend.

5.2.2 Preparing the experiment

All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

Pipe network water connection

Pipe element Pipe element
connection connection 180°

25mm x 1,9mm

20mm x 1,5mm

20mm x 1,5mm

16mm x 1,8mm

16mm x 1,8mm

Supply valves Pipe element

outlet
Fig. 5.3 "Series connection" pipe network

1. Fit the "Series connection" pipe network on

the frame as shown in Fig. 5.3.
– Install sealing rings between the pipe ele-
ment and the pipe section.
2. Place the frame on the trainer.

5 Experiments 35
 HM 111 PIPE NETWORKS

3. Connect the hose to the water connection for

the pipe network.
– Install a sealing ring between the hose and
the water connection for the pipe section.
4. Close the supply valves for the pipe network.
5. Close the main valve.
6. Turn on the pump.
The experimental setup is now ready for use.
All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

5.2.3 Performing the experiment

Pressure measuring connection Pressure measuring connection

Supply valves
Fig. 5.4 "Series connection" pipe network

7. Open the main valve.

8. Open the supply valve for the pipe section to
create a flow through the pipe section.

5 Experiments 36
 HM 111 PIPE NETWORKS

If measuring using the 2-tube manometer:

9. Connect the pressure measuring connections
on the pipe section with a flow through it to the
2-tube manometer using hoses.
10. Bleed the hoses as described in
Chapter 3.4.1, Page 13.
11. If necessary, adjust the manometer for the
measurement as described in Chapter 3.4.2,
Page 14.
All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

Continue with step 14.

If measuring using the differential pressure

manometer:
12. Bleed the hoses as described in
Chapter 3.5.1, Page 16.
13. Connect the pressure measuring connections
on the pipe section with a flow through it to the
differential pressure manometer using the
hoses.

14. Note the following:

– Differential pressure or head loss
– Time elapsed for filling the measuring tank
with 10 L of water.
15. Close the supply valve.
16. Open the supply valve.
17. Repeat steps 10 to 16 twice with the same
main valve setting so that a total of three
measurements have been performed.
18. Change the flow using the main valve.

5 Experiments 37
 HM 111 PIPE NETWORKS

19. Repeat steps 10 to 18 until you have meas-

ured at least five different flows three times for
each pipe section.
20. Turn off the pump.
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5 Experiments 38
 All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

Experiment:

5.2.4
Date: 08.04.2015
HM 111
Name: Mittasch

5 Experiments
Pipe section / pipe element(s): "Series connection" pipe network
First section

1st iteration 2nd iteration 3rd iteration

hloss hloss hloss

ploss ploss ploss
Measure- in in in
V in L t in s in V in L t in s in V in L t in s in
ment mm mm mm
Measured values

bar bar bar

WC WC WC
PIPE NETWORKS

1 10 23,26 795-592 0,0203 10 23,16 794-592 0,0202 10 23,68 794-590 0,0204

2 10 25,06 763-585 0,0178 10 25,30 762-585 0,0177 10 24,77 762-584 0,0178

3 10 29,78 702-566 0,0136 10 29,42 697-568 0,0129 10 29,36 698-566 0,0132

4 10 32,68 658-555 0,0103 10 33,43 658-555 0,0103 10 33,34 656-553 0,0103

5 10 42,81 593-528 0,0065 10 42,31 592-530 0,0062 10 42,85 593-530 0,0063

39
 HM 111 PIPE NETWORKS

5.2.5 Evaluation of the experiment

The measured values recorded enable a "pres-

sure loss against flow" calibration curve to be pro-
duced for a bend.
The calibration curve is shown in the appendix to
the instructions. The measured values that form
the basis for the calibration curve have also been
used to calculate the constant K using
Formula (4.6), Page 21 and Formula (4.7),
Page 21. The flow is used in the unit m3/h.
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Example for highest flow:

p loss 20,3mbar - = 8,56

K total = -----------
- = -------------------------------
2 3 2
1,54  ---------
Q 2 m
 h 

Constant for the bend with mean values:

Ktotal = Kpipe + Kbend  Kbend = Ktotal -Kpipe

2
mbar  h -
K bend = 8,7 – 5,5 = 3,2 ------------------------
6
m

All measurements have been carried out a total of

three times.
Calculate the arithmetic mean for V, t and ploss.
Example for tm:

t1 + t2 + t3
t m = --------------------------
- (5.2)
3

5 Experiments 40
 All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

Experiment: Constants for bends

Date: 20.02.2015
HM 111
Name: Mittasch

5 Experiments
Pipe section / pipe element(s): "Series connection" pipe network
First section

Ktotal in p calc in
Measure- ploss in 2 Variation in
Vm in L tm in s Q in L/s Q in m3/h mbar mbar
ment mbar ----------------------
 h- mbar
m 6 for K = 8,7

1 10 23,37 20,3 0,4279 1,54 8,56 20,6 0,3

PIPE NETWORKS

2 10 25,04 17,8 0,3994 1,44 8,58 18,0 0,2

3 10 29,52 13,2 0,3388 1,22 8,87 13,0 -0,2

4 10 33,15 06,3 0,3017 1,09 8,67 10,3 0

5 10 42,66 10,3 0,2344 0,84 8,93 06,1 -0,2

Kpipe1 = 5,5 Kbend = 3,2

41
 HM 111 PIPE NETWORKS

5.2.6 Evaluation of experiment

The series connection example shows how pipe

networks are to be investigated taking into
account the constant K:

Q
5,5 3,2

3,2 15 3,2
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3,2 15 3,2

3,2 90 3,2

Q
3,2 90

Fig. 5.5

As there is a series connection, the different

resistances are simply added together, leading to
2 6
a Ktotal of 241,1mbar  h  m .
The value is multiplied by the square of the meas-
ured flow and thus provides the pressure loss
(using the flow value in m3/h).
The following table shows the values measured
on the pipe network and the pressure losses cal-
culated using Formula (4.6), Page 21.

5 Experiments 42
 All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

Experiment: Constants for bends

Date: 09.04.2015
HM 111
Name: Mittasch

5 Experiments
Pipe section / pipe element(s): "Series connection" pipe network

1st iteration 2nd iteration 3rd iteration

hloss in hloss in hloss in

Measure- ploss in ploss in ploss in
V in L t in s mm W V in L t in s mm W V in L t in s mm W
ment mbar mbar mbar
C C C

1 10 23,42 0,555 10 23,63 0,560 10 23,21 0,555

PIPE NETWORKS

2 10 25,50 0,495 10 25,16 0,485 10 24,92 0,495

3 10 26,98 0,405 10 27,51 0,400 10 27,63 0,400

4 10 30,89 0,295 10 30,44 0,305 10 30,47 0,305

5 10 39,82 0,200 10 39,52 0,190 10 39,97 0,190

43
 All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

Experiment: Constants for bends

Date: 09.04.2015
HM 111
Name: Mittasch

5 Experiments
Pipe section / pipe element(s): "Series connection" pipe network

p calc in
Ktotal in
Measure- ploss in 2 mbar where Variation in
Vm in L tm in s Q in L/s Q in m3/h mbar
ment mbar ----------------------
 h- Ktotal = 241, mbar
m6 1

1 10 23,42 557 0,4270 1,54 234,9 572 15

PIPE NETWORKS

2 10 25,09 492 0,3986 1,43 240,6 493 1

3 10 27,37 402 0,3654 1,32 230,7 420 18

Calculations

4 10 30,60 302 0,3268 1,18 216,9 336 34

5 10 39,77 193 0,2514 0,91 233,1 200 7

44
 HM 111 PIPE NETWORKS

NOTICE
To achieve greater accuracy in the flow measure-
ment, the time should be measured multiple times
at the same flow and the mean value calculated.
All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

5 Experiments 45
 HM 111 PIPE NETWORKS

6 Appendix

6.1 Technical data

Dimensions
Length x Width x Height 1550mm x 800mm x 1600 mm
Weight Approx. 117 kg

Power supply
Voltage 230 V
Frequency 50 Hz
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Phases 1
Nominal consumption (power) 0,8 kW
Optional alternatives, see rating plate

Pump
Power consumption 250 W
Flow rate, max. 9 m3/h
Head, max. 7,0 m

Pipe section A
Flow rate, max. 3 m3/h

Pipe sections
Length 700 mm each
Roughness  hydr. smooth k = 0,00125 mm
External diameter x Wall thickness 1x: 25mm x 1,9 mm
External diameter x Wall thickness 2x: 20mm x 1,5 mm
External diameter x Wall thickness 2x: 16mm x 1,8 mm

6 Appendix 46
 HM 111 PIPE NETWORKS

Supply tank
Volume 180 L

Measuring tank
For high flow rates 40 L
For low flow rates 10 L

Differential pressure manometer

Measuring range 0...1 bar
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Two-tube manometer
Measuring range 0...100 mbar

6 Appendix 47
 HM 111 PIPE NETWORKS

6.2 List of key symbols and units used

Symbol Mathematical/physical variable Unit

d Pipe diameter mm

g Acceleration due to gravity g = 10 m/s2

h Height mm, m

k Wall roughness / pipe roughness mm

K Constant

l Length mm
All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

p Pressure mbar

Re Reynolds number

t Time s, min

v Flow velocity

V Volume L

Q Flow L/min, L/s, m3/h

p Differential pressure mbar

 Pipe coefficient of friction --

 Kinematic viscosity m2/s

 Pi --

 Density kg/m3

Index Explanation

bend Bend

calc Calculated

loss Loss

m Mean value

pipe Pipe (straight)

total Total

6 Appendix 48
 HM 111 PIPE NETWORKS

6.3 Tables

Unit mm3 cm3 L m3

1mm3 1 0,001 0,000001 0,000000001

1cm3 1.000 1 0,001 0,000001

1L 1.000.000 1.000 1 0,001

1m3 1.000.000.000 1.000.000 1.000 1

Tab. 6.1 Conversion table for units of volume

All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

Unit L/s L/min L/h m3/min m3/h

1 L/s 1 60 3600 0,06 3,6

1 L/min 0,01667 1 60 0,001 0,06

1 L/h 0,000278 0,01667 1 0,00001667 0,001

1m3/min 16,667 1000 0,0006 1 60

1m3/h 0,278 16,667 1000 0,01667 1

Tab. 6.2 Conversion table for volumetric flow units

Unit bar mbar Pa hPa kPa mm WC *

1 bar 1 1.000 100.000 1.000 100 10.000

1 mbar 0,001 1 100 1 0,1 10

1 Pa 0,00001 0,01 1 0,01 0,001 0,1

1hPa 0,001 1 100 1 0,1 10

1 kPa 0,01 10 1.000 10 1 100

1 mm WC * 0,0001 0,1 10 0,1 0,01 1

Tab. 6.3 Conversion table for pressure units

* Rounded values

6 Appendix 49
 HM 111 PIPE NETWORKS

Temperature Kinematic viscosity

in °C in 10-6m2/s

15 1.134

16 1.106

17 1.079

18 1.055

19 1.028

20 1.004

21 0.980
All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

22 0.957

23 0.935

24 0.914

25 0.894

26 0.875

27 0.856

28 0.837

29 0.812

30 0.801

Tab. 6.4 Kinematic viscosity  of water depending on

temperature
(Based on Kalide: Technical Fluid Mechanics)

6 Appendix 50
 HM 111 PIPE NETWORKS

6.4 Pipe coefficient of friction

Unstable

Limit curve
All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

Sm
oot
h pip
es
(k
laminar turbulent =0
)

Fig. 6.1 Pipe coefficient of friction based on Colebrook and Nikuradse

(from Dubbel, Taschenbuch für den Maschinenbau [Engineering handbook])

6 Appendix 51
 HM 111 PIPE NETWORKS

6.5 Worksheets

6.5.1 Formulae

Mean value of a measured variable

t 1. measurement + t 2. measurement + t 3. measurement

t m = --------------------------------------------------------------------------------------------------------------------- in s for three iterations
3

t 1. measurement + t 2. measurement
t m = ---------------------------------------------------------------------------
- in s for two iterations
2
All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

The process is similar for Vm and p loss,m .

Conversion of head loss into pressure loss

(simplified with acceleration due to gravity g = 10m/s2)

h loss
p loss = ---------------------
- in mbar with h loss in mm
mm
10 --------------
mbar

Volumetric flow calculation

L L
Q = V
---- in --- or ----------
t s min
3
Q = V  3600 in m
--------------------- ------- with V in L and t in s
t  1000 h
3
V  60- in m
Q = ------------------ ------- with V in L and t in min
t  1000 h

6 Appendix 52
 HM 111 PIPE NETWORKS

Constant for resistance

3
p loss m
K = -----------
- with p loss in mbar and Q in -------
Q
2 h

Constant in series and parallel connection

Series connection: K total = K 1 + K 2 + K 3 + ...

All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

1 1 1 1
Parallel connection: -------------------- = ------------ + ------------ + ------------ + ...
K total K1 K2 K3
1
K total = ------------------------------------------------------------------------
-
 ------------
1 + ------------ 1 + ------------ 1 + ...  2
 
 K1 K2 K3 

Calculated pressure loss

3
2 m
 p calc = Q  K with Q in -------
h
2
mbar  h
and K in ------------------------
6
-
m

Variation

Variation = p calc – p loss with p calc in mbar

and p loss in mbar

6 Appendix 53
 All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

6.5.2
Experiment: ______________________________
Date: _______________
HM 111

6 Appendix
Name: _______________

Pipe section / pipe element(s): ______________________________________________________________

1st iteration 2nd iteration 3rd iteration

hloss in hloss in hloss in

Measure- ploss in ploss in ploss in
V in L t in s mm W V in L t in s mm W V in L t in s mm W
ment bar bar bar
C C C
Measured values

1
PIPE NETWORKS

54
 All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

Experiment: _________________________________________

6.5.3
Date: _______________
HM 111

6 Appendix
Name: _______________

Pipe section / pipe element(s):

______________________________________________________________
__

Ktotal in
Measure- ploss,m in 2 p calc in Variation in
Calculations

Vm in L tm in s Q in L/s Q in m3/h mbar

ment mbar ----------------------
 h- mbar mbar
m 6

1
PIPE NETWORKS

Kpipe = ____ Kbend = ____

55
 HM 111 PIPE NETWORKS

6.6 Pipe networks

25mm x 1,9mm

20mm x 1,5mm

16mm x 1,8mm
All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

Fig. 6.2 Calibration of pipe sections Fig. 6.3 Doubling

Fig. 6.4 Series connection Fig. 6.5 Parallel and series connection

Fig. 6.6 Ring Fig. 6.7 Parallel connection

6 Appendix 56
 HM 111 PIPE NETWORKS

6.7 Diagrams

6.7.1 Calibration curve for 25mm pipe (pipe section A)

60

50
All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

40
Pressure loss ploss in mbar

30

20

10

0
0 10 20 30 40 50 60

Flow Q in L/min

6 Appendix 57
 HM 111 PIPE NETWORKS

6.7.2 Calibration curve for 20mm pipe (pipe section B)

140

120

100
All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

Pressure loss ploss in mbar

80

60

40

20

0
0 10 20 30 40 50 60

Flow Q in L/min

6 Appendix 58
 HM 111 PIPE NETWORKS

6.7.3 Calibration curve for 16 mm pipe

450

400

350
All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

300
Pressure loss ploss in mbar

250

200

150

100

50

0
0 10 20 30 40

Flow Q in L/min

6 Appendix 59
 HM 111 PIPE NETWORKS

6.7.4 Calibration curve for bend

35

30

25
All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 06/2015

Pressure loss ploss in mbar

20

15

10

0
0 10 20 30 40 50 60

Flow Q in L/min

6 Appendix 60