APPLIED FLUID MECHANICS
C7 Pipe Surge and Water Hammer Apparatus - Issue 11
Pipe surge and water hammer are two related but independent phenomena which arise when fluid flowing in a pipe is accelerated or decelerated. The associated pressure transients can be damaging to pipework or components and systems must be designed to avoid or withstand them.
The equipment designed by Armfield clearly demonstrates the different effects resulting from gradual or instantaneous changes in fluid velocity (created by slow and fast valve closure). Effect of initial fluid velocity can also be investigated.
Pipe surge resulting from a gradual change in fluid velocity is clearly seen as fluctuating changes in head in a surge shaft.
Water hammer resulting from a rapid change in fluid velocity is clearly seen as large changes in pressure monitored using a pair of transducers and indicated using an oscilloscope.
ORDERING SPECIFICATION
C7-10, C7-11, C7-11A
• A self-contained unit designed to demonstrate the phenomena of pipe surge and water hammer.
• The unit includes two separate test pipes, service module and constant head tank.
• Two pressure transducers provide electrical signals for connection to a dual trace storage oscilloscope with an integral printer output.
• Straight pipes are used, rather than a coiled arrangement, to reduce distortion of the pressure wave.
Demonstration Capabilities
> demonstration of pipe surge
> determination of oscillatory characteristics of the surge shaft
> demonstration of frictional head loss between reservoir and surge shaft
> comparison between theoretical and measured pressure profiles produced
by water hammer
> using a dual trace storage oscilloscope to record transient water hammer
pressure profiles
> measuring the pressure profile characteristics
> determination of the velocity of sound through a fluid in a pipe
> demonstration of the effects of cavitation on subsequent cycles.
Description
The equipment comprises two stainless steel pipes connected to a constant head tank. A service module provides the water supply to the head tank and also incorporates a volumetric tank for flow rate measurement, sump tank, circulating pump and flow control valve.
Water enters the two test pipes via the constant head tank and discharges into the volumetric tank. A dump valve in the volumetric tank returns the water to the sump tank.
The pipe surge test section incorporates a clear acrylic surge shaft to enable visualisation of its oscillatory characteristics to be demonstrated.
A metric scale on the shaft permits the height of the oscillations to be measured. The test pipe terminates with a lever operated gate valve and separate flow control valve.
The water hammer test section uses a unique fast acting valve specifically designed by Armfield.
A moving shuttle within the valve travels with the water flow, thereby enabling a very high closure rate to be obtained. The valve can easily be operated simply by pressing the valve release button, and a spring loaded plunger re-sets it for further use. Straight pipes are used, rather than a coiled arrangement, to reduce the distortion of the pressure wave.
Pressure transducers mounted at the fast acting valve itself and at a point along the test pipe provide analogue outputs which are fed into a signal conditioning module. The corresponding output voltage from the signal conditioning module can then be fed into a dual trace oscilloscope (C7-11A). A USB output is available from the oscilloscope. This allows the stored display to be transferred onto a suitable printer (C7-12) to provide a hard copy of the transient.
The pipe surge (C7-10) part of the apparatus may be ordered separately, with the water hammer (C7-11) being added at a later stage if required.
Technical details
| C7-10 | details |
|---|---|
| Pipe surge test pipe: | stainless steel 22mm I/D x 3m long |
| Surge shaft: | clear acrylic 40mm I/D x 800mm H |
| Service pump: | centrifugal type, delivering 1.35 litres/sec at 3m H2O |
| Flow rate measurement: | volumetric tank, stepped 0-40 litre high flows 0-6 litre low flows |
| Head tank: | capacity 45 litres made from PVC. |
| C7-11 | details |
|---|---|
| C7-11 Water hammer test pipe: |
stainless steel 22mm I/D x 3m long |
| Pressure transducers: | 2 off range 1 to 69 bar, .25" BSP connections |
| C7-11A | details |
|---|---|
| C7-11A Oscilloscope |
dual trace storage oscilloscope with USB output |
| C7-12 | details |
|---|---|
| C7-12 Printer |
with USB interface for use with C7-11A |
Ordering Options
C7-10
Self-contained pipe surge apparatus only
C7-11
Water hammer apparatus, additional to C7-10
C7-11A
Oscilloscope for C7-11
C7-12
Printer for C7-11A
Requirements
Electrical supply:
Electrical supply:
C7-10-A: 220-240V/1ph/50Hz
C7-10-B: 120V/1ph/60Hz
C7-10-G: 220-240V/1ph/60Hz
C7-11-A: 220-240V/1ph/50Hz
C7-11-B: 120V/1ph/60Hz
C7-11-G: 220-240V/1ph/60Hz
C7-12-A: 220-240V/1ph/50Hz
C7-12-B: 120V/1ph/60Hz
C7-12-G: 220-240V/1ph/60HZ
Shipping specification
C7-10:
Volume: 2.5m3
Gross weight: 300kg
C7-11:
Volume: 0.5m3
Gross weight: 20kg
C7-11A:
Volume: 0.1m3
Gross weight: 10kg
C7-12:
Volume: 0.1m3
Gross weight: 10kg
Overall dimensions
Height: 1.865m
Length:3.875m
Depth: 0.725m
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