SPX Cooling Technologies TG MAG86-100 Benutzerhandbuch

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A.0500.551 – IM-TGMAG/02.00 EN (02/2008)

•  Use piping with a diameter equal to or greater than the connection ports of the pump and with 

the shortest possible lengths.

•  The pipe diameter has to be calculated in function of the liquid parameters and the installation

parameters. If necessary use larger diameters to limit pressure losses.

•  If the fluid to be pumped is viscous, pressure losses in the suction and discharge lines may  

increase considerably. Other piping components like valves, elbows, strainers, filters and foot 
valve also cause pressure losses.

•  Diameters, length of piping and other components should be selected in such a way that the

pump will operate without causing mechanical damage to the pump/pump unit, taking into  
account the minimum required inlet pressure, the maximum allowable working pressure and the 
installed motor power and torque.

•  Check the tightness of the pipes after connection.

•  Liquids should enter the pump from a level higher than the pump level, the inclining pipe should 

rise upwards towards the pump without any air pockets.

•  A too small diameter or a too long suction pipe, a too small or blocked strainer will increase

pressure losses so that the NPSHa (NPSH available) becomes smaller than the NPSH (NPSH 
required). 

 

Cavitation will occur, causing noise and vibrations. Mechanical damage to pump and pump unit 
may occur.

•  When a suction strainer or filter is installed pressure losses in the suction line must be checked

constantly. Also check if the inlet pressure at the suction flange of the pump is still sufficiently 
high.

 

At the start sufficient liquid must be available in the pump filling up the internal clearance volume and 
the dead spaces, allowing the pump to build up a pressure difference.

Therefore, for pumping low viscosity fluids, a foot valve with the same or larger diameter than the 
suction pipe must be installed or the pump can be installed without foot-valve but in U-line.

•  To remove air and gases from suction line and pump, counter pressure at the discharge side

must be reduced. In case of self-priming operation, start-up of the pump should be performed 
with open and empty discharge line allowing air or gases to escape at low backpressure.

•  Another possibility in case of long lines or when a non-return valve is installed in the discharge

line, is to install a by-pass with isolating valve close to the discharge side of the pump. This valve 
will be opened in case of priming and allows air or gas evacuation at low backpressure. 

•  The bypass should be lead back to the supply tank – not to the suction port.

To allow proper maintenance it is necessary to be 
able to isolate the pump. Isolation can be done by 
installing valves in suction and discharge lines.

•  These valves must have a cylindrical passage of

the same diameter of the piping (full bore). (Gate 
or ball valves are preferable).

•  When operating the pump, the valves must  

be opened completely. The output must never  
be regulated by means of closing valves in  
suction or discharge pipes. It must be regulated 
by changing shaft speed or by re-routing the 
media over a by-pass back to the supply tank.