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 HM 155 Water Hammers in Pipes
 Technical Description

Water hammers in pipes are a significant problem in engineering as they can cause severe damage to piping, fittings and system components. The water hammers are caused by the inertia effect of the flowing fluid at abrupt changes in velocity, e.g. when rapidly closing a valve. Therefore, knowledge about the emergence of water hammers is an important aspect of designing pipework systems.
The HM 155 trainer can be used to study water hammers and pressure waves in long pipelines. The water hammers are generated by closing a valve at the end of the pipe section. These water hammers are then reflected to the beginning of the pipe as an inverted wave. A pressure tank with air cushion at the start of the pipe section simulates the open beginning of the pipe, so that there is a clear reflection of the wave. In order to achieve reflection times that are large enough, a 60m long pipe section has been installed, which is shaped as a coiled tube to save space.
In experiments, the emergence of water hammers is studied as a function of the valve closing times. The trainer therefore includes two solenoid valves, one with constant closing time and one with adjustable closing time. The resulting pressure vibrations are measured by a pressure sensor and the pressure curve is displayed by the LabVIEW software.

A valve is used to adjust the flow rate. System pressure and flow rate are displayed. A safety valve protects the system against excess pressure.
The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.

Learning Objectives / Experiments
- water hammers as a function of flow rate
- water hammers as a function of valve closing time
- display pressure curve
- determine reflection time
- calculation of the velocity of sound in water
 Features

* Investigation of water hammers and pressure

waves in pipes1
* 60m long pipe section1
* Measuring the velocity of sound in water1
* Solenoid valve with adjustable closing time1
* Software for displaying the pressure curve

 Alternative products
HM 150.15 -- Hydraulic Ram – Pumping Using Water Hammers
HM 156 -- Water Hammers and Surge Chamber
 Specification [1] investigation of water hammers and pressure waves in pipes[2] pipe section as coiled tube to save space[3] generation of water hammers via solenoid valve with constant closing time[4] generation of water hammers via solenoid valve with adjustable closing time[5] pressure tank with air cushion reflects the wave[6] safety valve protects against excess pressure in the system[7] instruments: Pressure sensor, rotameter, manometer [8] representation of the pressure curves with LabVIEW software[9] LabVIEW software for data acquisition via USB under Windows XP or Windows Vista Technical Data Solenoid valve, constant closing time- closing time: 20...30ms- operating pressure: 0...10barSolenoid valve, adjustable closing time- closing time: 1...4s- operating pressure: 0,2...12barSafety valve: 16barPipe section, copper- l=60m - di=10mm Measuring ranges- pressure: 0...10bar- flow rate: 30...320L/h Dimensions and Weight LxWxH: 1.350x760x1.460mmWeight: approx. 147kg Required for Operation 230V, 50/60Hz, 1 phase or 120V, 50/60Hz/CSA, 1 phase Water connection 300L/h, drain Scope of Delivery 1 trainer1 CD with LabVIEW software1 set of hoses1 set of instructional material Order Details 070.15500  HM 155  Water Hammers in Pipes