7
5.2 Piping System
1. All systems should include a pressure relief valve on the discharge side, to protect
piping and process equipment, including the pump, from excess process
pressures. An external relief valve is required! There should be no devices capable
of restricting flow (such as a valve) located between the pump and the relief device.
2. Shutoff valves and unions (or flanges) on suction and discharge piping are
recommended. This permits check valve inspection without draining long runs of
piping, making periodic maintenance and inspection easier.
3. Shutoff valves should be of the same size as connecting pipe. Ball valves are
preferred since they offer minimum flow restriction.
4. Suction systems should include an inlet strainer, if appropriate for the product being
pumped. Pump check valves are susceptible to dirt and other solid contaminants, and
any accumulation can cause malfunction. The strainer should be located between the
suction shutoff valve and the pump suction valve. It must be sized to accommodate
the flow rate and the anticipated level of contamination. A 100 mesh screen size is
generally recommended.
5. Vacuum/pressure gauges in the suction and discharge lines are helpful in order to
check system operation. Gauges should be fitted with protective shutoff valves for
isolation while not in use.
6. Piping weight must not be supported by valve housings or other portions of the
reagent head, as the resulting stresses can cause leaks. If appropriate, provide for
thermal expansion and contraction so that no excess force or moments are applied
to the pump.
7. In piping assembly, use a sealing compound chemically compatible with the process
material. Users of sealing tape are cautioned to ensure that the entering pipe thread
ends are not taped, and that tape is removed from previously-used threads to the
maximum practical extent prior to re-use. 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. Debris from the piping system
that prevents proper check valve operation is a common startup issue.
5.3 Suction Pressure Requirements
Although GLM® DM7 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 or less (at
operating temperature) the wet suction lift capability is approximately ten (10) feet. 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 under suction lift conditions may require some liquid priming
before they will operate reliably.
Summary of Contents for PULSA GLM7
Page 23: ...22 Figure 14 Check valves metal construction...
Page 30: ...29 12 Dimensional Draw ings...
Page 31: ...30...
Page 32: ...31 13 Parts Diagrams and Parts Lists...
Page 35: ...34...
