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A.0500.551 – IM-TGMAG/02.00 EN (02/2008)
3.2.1 Self-priming operation
TopGear pumps are self-priming when sufficient liquid is present in the pump to fill up the
clearances and the dead spaces between the teeth. (For self-priming operation see also section
3.18.5.2 Piping).
3.2.2 Safety relief valve – Working principle
The positive displacement principle requires the installation of a safety relief valve
protecting the pump against overpressure. It can be installed on the pump or in the installation.
(See 3.19.4 Checklist – Initial start-up – Safety relief valve)
This safety relief valve limits the differential
pressure (∆p) between suction and discharge,
not the maximum pressure within the installation.
For example, as media cannot escape when
the discharge side of the pump is obstructed,
an over-pressure may cause severe damage
to the pump. The safety relief valve provides
an escape path, rerouting the media back to
the suction side when reaching a specified
pressure level.
• Thesafetyreliefvalveprotectsthepumpagainstover-pressureonlyinoneowdirection.
• Anopensafetyreliefvalveindicatesthattheinstallationisnotfunctioningproperly.Thepump
must be shut down at once. Find and solve the problem before restarting the pump.
• Whenthesafetyreliefvalveisnotinstalledonthepump,otherprotectionsagainstoverpressure
must be provided.
• Note! Do not use the safety relief valve as a flow regulator. The liquid will ciculate only through
the pump and will heat up quickly.
Contact your distributor if a flow regulator is required.
3.3 Sound
TopGear pumps are rotary displacement pumps. Because of the contact between internal parts (ro-
tor/idler), pressure variations etc. they produce more noise than for example centrifugal pumps. Also
the sound coming from drive and installation must be taken into consideration.
As the sound level at the operating area may exceed 85 dB(A), ear protection must be worn.
See also section 3.7 Sound level.
3.4 General performance
Important!
The pump is calculated for the liquid transport as described in the quotation. Contact your distributor
if one or several application parameters change.
Liquids not suitable for the pump can cause damage to the pump unit and imply risk of personal
injury.
Correct application requires that consideration be given to all of the following:
Product name, concentration and density. Product viscosity, product particles (size, hardness,
concentration, shape), product purity, product temperature, inlet and outlet pressure, RPM, etc.