Power Failure; Technical Information: Field Devices; General; Gas Detectors - Crowcon Vortex Installation, Operation And Maintenance Manual

4.7.5 Power Failure

Under total power failure all system configuration data is protected by non-volatile
Ferroelectric RAM (FRAM) in the Node Controller Module. Logged data is not protected and
is lost.
The power status is displayed by the Power Healthy LED on the Display Module, where
fitted.
Detectors have a warm-up time when power is initially connected or reconnected after a
power loss. During this period, detector signals may not be reliable.
ICES

5 TECHNICAL INFORMATION: FIELD DEVICES

5.1 General

This chapter contains detailed technical information on the use of field devices (detectors and
audible and visible alarms) with Vortex. You may need to refer to this during installation,
configuration or maintenance of the Vortex system.
If you simply use Vortex for monitoring and responding to alarms, it is not necessary to read
this chapter. See chapter 6, Operation.

5.2 Gas Detectors

5.2.1 Gas detector location

There are no rules that dictate the siting and location of detectors. However, considerable
guidance is available from:
 BS EN 50073:1999, Guide for Selection, Use and Maintenance of Apparatus for the
Detection and Measurement of Combustible Gases or Oxygen.
Similar codes of practice of other countries may be used where applicable. In addition,
certain regulatory bodies publish specifications giving minimum gas detection requirements
for specific applications.
The detector should be mounted where the gas is most likely to be present. The following
points should be noted when locating gas detectors:
 To detect gases that are lighter than air, for example, methane, detectors should be
mounted at high level. Crowcon recommends the use of a Collector Cone.
 To detect gases that are heavier than air, for example, butane, detectors should be
mounted at low level. Contact Crowcon for details.
 To detect gases with similar weight to air, for example, hydrogen sulphide, mount the
detector at normal breathing height.
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