GDS GDS-68XP, Operation And Maintenance Manual

Page: 21 / 68

GDS-68XP Operation & Maintenance Manual, Revision 3.5
Page 21
FILTER DRAIN & FILTER BYPASS
All GDS ‐ 68XP configurations include a coalescing filter with stainless steel drain valve. For positive
pressure models, the drain valve should be opened periodically to release any built ‐ up liquid that may
have been trapped inside the filter. Conversely, the filter drain valve may be left ‘cracked open’ to allow
moisture (and sample gas) to escape on a continuous basis.
Models with the combination coalescing and membrane filter include a bypass valve that should be
opened slightly to maintain a constant flow of sample across the membrane element to carry away
moisture and particulates captured by the filter.
Figure 5-7: Filter Drain & Exhaust Tubing Recommendations
NOTE : LEAVING THE FILTER DRAIN VALVE ‘CRACKED’ OPEN WILL ALLOW SAMPLE GAS TO FLOW FROM
THE PICKUP POINT TO THE GDS ‐ 68XP ON A CONTINUOUS BASIS, ENSURING THAT FRESH SAMPLE IS
ALWAYS AVAILABLE AT THE BEGINNING OF EACH NEW SAMPLE SEQUENCE.
Filter Drain Recommendations
1) Including a length of clear tubing in the
filter drain line makes it easy to monitor
the drain for the presence of moisture
2) Filter drain and filter bypass drain can be
combined in the same manifold
3) Filters in sample draw units should only be
drained during sample purge or purge /
hold times to keep ambient air from being
drawn into the GDS ‐ 68XP by the sample
pump
IMPORTANT : DO NOT TIE SAMPLE EXHAUST
TO A COMMON EXHAUST MANIFOLD.
MAINTAIN A SEPARATE SAMPLE EXHAUST
LINE TO AMBIENT AIR.
Filter
Drain
Filter
Bypass
Sample
Exhaust
IMPORTANT : MAKES SURE SAMPLE EXHAUST
IS DIRECTED TO A SAFE AREA