28
Flowserve US Inc.
SIHI
dry
dry
dry
dry
Standard
Standard
Standard
Standard M Series
Dry Running Vacuum Pump
Issue Date: November 21, 2016 Copyright:
FLOWSERVE SIHI Pumps Rev 1
3.6 Functional Description Purge Gas System [Pressurized & Purged Enclosure acc. NFPA496]
The purge gas system enables the application
of the SIHIdry system in explosive areas (Class
1 Division 1, 2). It consists of a purge gas
monitoring device connected to the vacuum
pump enclosure. After adequate purge gas
pressure has been attained, a switch contact
that is to be evaluated in a supply by the
Operating Company is closed. All supply
voltages, inputs and outputs to the pump must
be isolated when purge contact is open by the
Operating Company.
Penetration of an explosive mixture into the
motor compartment and electronic casing is
prevented by maintaining the inflammation-
protection gas, nitrogen, at an excess pressure
in these compartments. A differential pressure
switch is installed to monitor the pressure
difference of the discharge of the pump
chamber and the electrical casing. If the
discharge pressure becomes greater than or
equal to the electrical casing pressure the
SIHIdry system shuts down. All necessary
purge settings are preset by manufacturer and
must not be changed.
Supply Pressure, Gas Specifications:
Clean Dry Oil Free Air or Inert Gas (N2) - Class 2-4-1 acc. DIN ISO 8573-1: 2010.
Maintained between 3-8 barg (44-116 psig), regulator fitted by others.
Purge gas and separate supply for logic circuits used, then: Logic supply to be maintained between 3-8 barg
(44-116 psig), regulator fitted by others.
For more information please consult the D707 mini-Purge Manual ML546.
Purge Gas
Monitoring
Device
Purge Gas IN
Figure 11: Purge Gas Control Unit
Summary of Contents for SIHI dry Standard H Series
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