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ML442 | v5k
Expo Technologies UK
T: +44 (0) 20 8398 8011
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b) LC - Leakage Compensation
Initially a high flow of protective gas is passed through the enclosure. 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 flow of protective gas is provided via an adjustable valve so that it
just compensates for any leakage from the PE in addition to maintaining its pressurization.
If leakage is less than 5 l/min then the LCV will be awkward to set. You will find that the RLV
spring will cycle open and closed. If this happens contact our service department for advice.
Figure 4 Leakage Compensation Circuit Diagram
3.5 Type of Output
The functions of the outputs are power control and alarm/pressurized indication. Power control
provides a signal to switch the power to the PE. Alarm output provides a passive signal to
indicate remotely when the enclosure is not pressurized and an active signal when pressurized.
a) PO- Pneumatic Output
The power control and pressurized outputs are pneumatic signals, which may be used to
operate other devices to provide power switching or alarm indication. The lack of any output
signal indicates incomplete purge and alarm. In many instances these outputs may be
connected to the Expo range of MiniPurge
Interface Unit s (MIU).
Figure 5 Typical MiniPurge Interface Unit
type (MIU/dA)
Figure 6 Pneumatic Output Option
