Servomex NanoTrace DF-760E, Инструкция по эксплуатации

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Appendix B – Hydrogen Service Safety System DF-760E 173
15 Appendix B
– Hydrogen Service
Safety System
The Hydrogen Service Safety System is designed to safeguard the DF-760 from
explosion hazards when operating on hydrogen sample gas under normal pressure and flow
conditions as described in this manual. The instrument chassis and the remote pump, if
equipped, are both protected by maintaining a safe condition within their respective
enclosures.
If equipped with this option at the time of shipment from the factory, the analyzer will be
set for Hydrogen operation through the GSF screen and the Hydrogen Safety Service
System will automatically be enabled.
15.1
Instrument

Air circulation fans pull air in through the front door (and vent through the rear)
of the chassis. The fans are rated at 50 cfm (125 cfm max) which will maintain the
internal chassis space below the lower explosive limit (LEL)
1
.

Sample delivery interlock valve blocks flow of sample gas from entering the
instrument chassis under various conditions as described below. It consists of a
normally closed pneumatically actuated UHP springless diaphragm valve
positioned on the sample inlet bulkhead.

Analyzer case purge valve introduces nitrogen purge flow into the chassis upon
closure of the sample delivery interlock valve. It consists of a normally open
pneumatically actuated valve which feeds a customer supplied and regulated source
of nitrogen purge gas through a bulkhead on the rear of the cabinet.
2

Instrument controls and logic
3
default, manage and actuate the above mentioned
components to maintain safe operating conditions.
15.2
Vacuum Pump

If equipped with a vacuum pump, an enclosure equipped with a nitrogen case
purge is provided to maintain a safe condition. In addition, an interlock is provided
to detect and react to loss of Nitrogen purge flow. See Figure 146 on page 178.
15.3
Installation
If equipped with this safety system, the analyzer installation procedure is modified as
follows:

If the analyzer has the optional vacuum pump, the pump enclosure must be
mounted to a nearby wall or inside the rack shared by the analyzer. See Figure 146
on page 178.