Avoidance of Water Trapping in Flame Detectors

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Abstract

Flame Detectors are safety equipment and downtime because of faults should be avoided when
possible. In outdoor applications, regularly temperature differences occur and Flame Detector
housings can suffer from damaged seals and moisture trapping, which, in turn, can cause electronics
faults. These faults can be avoided with a Pressure Compensating Element, (PCE). This document is
explains how PCE’s work and discusses how they are a solution to the water trapping problem.

Problem Statement

Pressure differences occur when a sealed housing is exposed to rapid, extreme or recurring changes
in ambient temperature conditions. Changing weather conditions, can cause a pressure difference
between the inside and the outside of a sealed housing. A rapid decrease in temperature, for example,
can create a vacuum inside the housing. If this pressure difference is not compensated, the vacuum
causes stress on the housing seal. This may cause seals to fail, allowing moisture trapping inside the
housing. This trapped moisture can cause faults in the electronics of a Flame Detector.

Background

In this section, the operation of PCE’s and the importance of their use are discussed.

Synonyms

There are several synonyms for pressure-compensating elements. The most common are Breather,
PCE, Protective Vent, Pressure Balance Element, Pressure Equalizing Element and Pressure
Compensating Drainage Element.

Principle of operation

For a housing without pressure compensation, the interaction of temperatures, with the influence of
water and moisture, may result in moisture being sucked into the housing through the seal. This may
cause a seal to fail and then Ingress Protection, (IP), is no longer guaranteed. High humidity and
condensation of water in the housing must be avoided. Constant balancing of pressure and the
exchange of air is required.

The simple solution, to this potential problem, is by use of a PCE to prevent prevent the formation of
condensation in the housing and damage to the seal. This prevents differences in pressure due to
temperature variations, guaranteeing trouble-free operation.

The PCE used in Sense-WARE Flame Detector housings is water-tight but air-transmitting, due to a
hydrophobic and air transmissive membrane. As the membrane is air transmitting, the temperature
difference between the interior and the outside of the housing does not result in a pressure difference.
Without a pressure difference over the seal, there is no air flow. Additionally, the membrane is
protected against puncture by screw drivers or other sharp toolss used during the commissioning of
the Flame Detector.

Features of the PCE:
  • Dustproof and waterproof protection, (Ingress Protection: IP66), is maintained regardless of temperature differences between the air in the housing and the ambient air temperature
  • The PCE allows compensation of pressure differences, arising from temperature changes, between the interior air and the surrounding air
  • The PCE contains a hydrophobic and air transmissive membrane, which prevents water molecules entering the housing
  • The PCE’s hydrophobic foil is protection and cannot be damaged by tools, such as screwdrivers or wrenches
  • No maintenance is required
Conclusion

Water trapping in a Flame Detector housing is a potential source of downtime and damage to the
electronics. These issues can be overcome with the help of a PCE. All Sense-WARE Flame Detectors
are fitted with a PCE.

References
  1. Protective Vents – Pressure Video (2014) Gore®, https://youtu.be/x832kshrYio
  2. https://www.gore.com/products/gore-protective-vents-for-lighting-housings
  3. https://en.wikipedia.org/wiki/Hydrophobic_effect
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