UH239
UH239 Series
H I G H P R E S S U R E F I LT E R S
s e r v i c e
i n s t r u c t i o n s
3
4.8
Bleed the UH239 filter assembly by opening the vent
plug (7) at the top of filter one and one half turns. Jog
system and fill filter until all air bleeds through the plug,
then torque tighten the vent plug to 12 ft/lb or 16 Nm.
Pressurize system fully and check for leaks; if leaks occur
refer to section 5.
5
Routine maintenance
5.1
Pall
filter assembly’s do not normally require special
attention except for periodic monitoring of the differential
pressure warning device. Schedule replacement of the
filter element every six months or sooner, and have ample
supply of spare elements available.
5.2
If external leakage is noted, replace O-ring at leak. If
leakage persists, check sealing surfaces for scratches
or cracks; replace any defective parts.
5.3
Differential pressure devices actuate when the element
needs changing or because of high fluid viscosity in
'cold start' conditions. If 'cold start' conditions exist,
see Section 6.2 and 6.3.
5.4
A dirty system can quickly plug a new filter element,
especially with
Pall
high efficiency filter media. It may
require one or two initial filter element changes to
stabilize element service life. If element service life is
short or differential pressure is excessive, the filter
assembly may be undersized; refer to the sizing and
selection section of the product literature or contact your
local Pall representative.
5.5
Make sure element change labels are clean and
undamaged. Replace illegible labels with the
appropriate new labels.
6
Differential pressure devices
Reference should be made to product literature for dimensions,
operating parameters, part numbering, ordering information
and specifications.
6.1
Differential pressure devices actuate when the filter
element needs changing or because of high fluid
viscosity in 'cold start' conditions.
6.2
If visual indicator is fitted and actuates during 'cold start'
(red button extends 5mm, 3/16"), reset by depressing the
button when the normal operating temperature is reached.
If indicator actuates after resetting, replace element.
NOTE: Option 'P' visual indicator has thermal lockout and
manual reset. No signal below 0°C (32°F), signal above
29°C (80°F).
6.3
If the electrical switch actuates (e.g. red light comes on)
during cold start, continue operating until the signal (red
light) goes out as system warms to normal operating
temperature. This feature can be used as 'warm up'
indication in operating procedures. If the warning signal
(red light) remains or appears when system is warm,
replace the filter element.
ENGLISH
6.4
Use of both positive indication (green light) and negative
indication (red light for dirty element) is recommended to
effectively monitor filter element life.
Electrical connections and ratings for all differential
pressure switch options:
110 VAC
=
4A (inductive),
4A (resistive)
220 VAC
=
4A (inductive),
4A (resistive)
28 VDC
=
3A (inductive),
5A (resistive)
48 VDC
=
1A (inductive),
1.5A (resistive)
125 VDC
=
0.25A (inductive),
0.5A (resistive)
Maximum inrush - 24 amps.
Underwriter’s lab. Inc. listed ratings of pressure switch
(Microswitch) options are:
4 amps at 250 VAC
0.25 amp resistive at 220 VDC
0.50 amp resistive at 110 VDC
Electrical differential pressure switch operation:
When preset differential pressure is exceeded continuity
switches from 'C' - 'A' to 'C' - 'B'.
When differential pressure decreases below the pre-set value,
continuity returns to 'C' - 'A'.
Figure 1
- Switch Circuit Diagram
C
or black
or tag 2
CAUTION:
Failure to bleed the filter housing adequately will
increase the dissolved air content of the system fluid
which will shorten fluid life and may cause other
problems in the system.
A
or white
or tag 1
B
or red
or tag 3
LOW DIFFERENTIAL PRESSURE
HIGH DIFFERENTIAL PRESSURE
