Mini-X-Purge Size 1 Manual ML 442 - Expo Technologies

3.2 Relief Valve (RLV)
The Relief Valve unit is fitted to the PE to provide a means of limiting the
maximum pressure experienced by the PE during operation. The RLV
model number has a suffix giving the diameter of the valve aperture in
millimetres e.g. RLV25 (= 25mm bore). The RLV also incorporates a
Spark Arrestor to prevent sparks being ejected from the PE into the
classified area.
In Leakage Compensation systems, the RLV is combined with the flow
measurement mechanism.
Figure 1. LC Relief Valve
3.3 Calibrated Outlet Orifice/Spark Arrestor (SAU)
Continuous Flow systems incorporate the SAU25. This unit has
a range of interchangeable calibrated orifice plates, which are
used to measure the flow through the PE.
3.4 The Methods of Pressurizing
Figure 2 Spark Arrestor Type SAU25
a) CF - Continuous Flow
A Continuous Flow (CF) of protective gas is passed through the PE. Initially this flow is verified
and performs the purging phase of the operation. When the purging phase is completed – i.e.
the purge time has elapsed- the same flow of protective gas maintains the pressurization of the
enclosure. This flow may be required to dilute an internal source of hazardous gas release.
Figure 3 Continuous Flow Circuit Diagram
ML 442 Issue 5C SP5115 09/11/12 ©
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