Expo-Telektron Safety Systems MiniPurge Z & Y Purge Manual ...

Expo-Telektron MiniPurge Z purge Handbook ML 307 Issue A Page 5-2
5.4.1 Control Unit (CU)
The control unit is at the heart of the system. It contains a pneumatic logic circuit specially
designed and built to control the functions required for purge and pressurization. For all
systems this includes pressure and purge flow measurement, and local visual indication of
alarm/pressurized and flow sensed. It also provides the output for remote alarm
corresponding to the output type selected.
5.4.2 Relief Valve (RLV)
The Relief Valve unit is fitted to the Pressurized Enclosure to provide a means of limiting the
maximum pressure experienced by the Pressurized Enclosure during operation. The RLV
model number has a suffix giving the diameter of the valve aperture in millimetres e.g. RLV25
(= 25mm/1” bore). It also incorporates a Spark Arrestor to prevent “sparks” being ejected
from the Pressurized Enclosure into the classified / hazardous area. When used with a
5.4.3 Spark Arrestor /Calibrated Outlet Orifice (SAU)
C:\Main System Files\Marketing\Memo\ML307 ISSUE A.doc
“Leakage
Compensation”
system, the RLV
also monitors the
calibrated “purging”
flow rate. The
Relief Valve design
is patented.
Figure 3 Relief
To measure the flow through a pressurized enclosure, the differential pressure across a
Figure 4 Spark arrestor type SAU25
Valve
restriction or orifice is measured. In
Leakage Compensation systems the flow
measurement is incorporated in the Relief
Valve. The continuous flow systems use
the SAU25, which has a range of
interchangeable calibrated orifice plates for
the purge flow measurement. Two SAU25
are supplied with a size 2 CF system.
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