Trebor 20 PURUS - Manual (Page 6)

PAGE 6 P20 PUMP OPERATION / MAINTENANCE MANUAL
3 TEMPERATURE AND PRESSURE LIMITS
3.1 HIGH TEMPERATURE OPERATION
The Purus 20 pump is molded out of virgin PFA. This enables high temperature operation
under specific conditions. The maximum temperature will vary in relation to the supply
pressure. Figure 3-1
shows Trebor’s maximum recommended temperature for the pump.
Exceeding the temperature for a corresponding supply pressure could cause the pump to
develop leaks at the pump main seal between the air and fluid chambers.
Figure 3-1: Purus 20 Recommended Temperature Curve
3.2 HIGH BACK PRESSURE OPERATION
Increasing the fluid outlet pressure, or back pressure, causes stress on the pump main
seal. High back pressure, around 90% of the supply pressure, can cause the pump to
develop leaks at the main seal. It is not recommended to run the Purus 20 pump at near
dead head conditions.
High back pressure and elevated fluid temperatures can combine to increase the
likelihood of pump failure due to a main seal leak. Higher temperature reduces the yield
strength of PFA, while higher stresses are induced by the high back pressure. The
combination of those two operating conditions can cause the main seal to unload, which
can lead to a leak. Due to the potential variations in operating conditions, the typical range
of material properties and the tolerance stack up, it is impossible to identify the exact
points where main seal leaks become probable due to temperature/back pressure
interactions.