Piping System Recommendations
1. When making the threaded joint to the valve cap assembly, use a sealing compound chemically
compatible with the process material (for example Loctite
®
8551 [Loctite
®
is a registered trade mark of
Henkel Corporation] for water service). Do not use sealing tape. The valve cap should be tightened by
hand and then tightened one additional turn (i.e., 360
°
) with the aid of an adjustable wrench.
2. Both new and existing piping should be cleaned, preferably by flushing with a clean liquid
(compatible with process material) and blown out with air, prior to connection to the pump.
Note - Debris from manufacturing the piping system (e.g., PVC shavings, TFE Tape, dirt, etc.)
can be unknowingly assembled inside the pipe. When fluid is introduced this material can be
transferred to the pump and prevent proper check valve operation. This is a common startup
issue.
3. Piping weight must not be supported by valve housings or other portions of the reagent head, as the
resulting stresses can cause leaks. Valve loads must not exceed 10 ft-lbf (13.5 n-m) moment or 5
lbf (22 n) in any direction. When temperature variations are expected provide for thermal expansion
and contraction of piping components so that force and/or moments are controlled within the
allowable range.
4. When making process connections, ensure that pipe joint cement and thread sealants do not run
into the check valve assemblies as this will inhibit valve operation. This is a common startup issue.
2.4 Suction Pressure Requirements
Although PULSA GLM metering pumps have some suction lift capability, a flooded suction (i.e., suction
pressure higher than atmospheric pressure) is preferable whenever possible. The pump should be
located as close as possible to the suction side reservoir or fluid supply source.
For fluid with a vapor pressure of 5 psia (0.35 bar) or less (at operating temperature) the wet suction lift
capability is approximately 10 ft (3 m). If this requirement is not met, the pump will not provide reliable,
accurate flow. In suction lift conditions, the use of a foot valve is recommended at the lowest point of
the pickup tube or pipe. Pumps operating under suction lift conditions may require some liquid priming
before they will operate reliably.
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