Packing Gland Adjustment - pick heaters 6X7 Service Manual

PICK VARIABLE FLOW SERVICE MANUAL
steam valve begins to open. At this
point read the pressure on the I-to-P
transducer outlet gauge.
5. A single steam valve or the small
valve on a dual assembly should
begin to open at 3-4 psi.
6. If the heater has a dual steam valve
arrangement, continue to increase
the controller output until the
second (larger) valve begins to
open. There should be a slight
amount of overlap between the
valves. The first valve should be
open about 90% (approximately 9
PSI) when the second valve starts to
open.
7. Most steam valves have an
adjustment nut at the top of the yoke
opening. Turning this into the
actuator body increases the opening
pressure. Unthreading the nut
reduces the air pressure to begin
opening the valve.
8. Return the temperature controller
output to zero or a negative value.
NOTE: There will be some error when
adjusting with the steam off because the
steam and water should be observed during
operation, and further adjustment may be
necessary.

PACKING GLAND ADJUSTMENT

Important: Consult Steam Valve Manual
for proper adjustment.
Packing gland adjustment is required when
either of two conditions exist:
1. Leakage around the valve steam
indicates a need to tighten the
packing gland nuts slightly or
replacing packing. Tighten evenly.
2. Fluctuations in product temperature
may be caused by excessive drag
between the packing gland and
steam valve stem. The steam valve
moves in a jerky motion. Slight
loosening of the packing gland nuts
may correct the condition.
WARNING: Loosen packing
gland nuts slightly. DO NOT
REMOVE NUTS
COMPLETELY! If steam leaks around
the packing gland, retighten the nuts until
the leakage stops.
OPERATION BELOW MINIMUM
STEAM VALVE TURNDOWN
Operating the heater at a steam flow that
requires the control valve to be less than
20% open can cause vibration, bounce,
flutter or hammer. If your application
requires operation under these conditions, a
dual steam valve assembly or a smaller
steam valve should be installed. Contact
Pick Heaters or your Pick representative for
more information.
NOTE: This situation can be checked by
throttling the steam block valve enough to
open the steam control valve at least 50%. If
the vibration ceases, the steam control valve
was operating too close to the seat.
AIR LEAKAGE
Air leaks between the steam valve actuator
and the temperature controller can result in
temperature controller problems. Leaks can
be detected by coating the area with a soap
solution. If bubbles form, a leak exists.
Repair all leaks.
Possible lead points to check include:
•
All air piping and connections
•
The steam valve diaghram may have
a hold in it.
•
The actuator stem O-ring may be cut
or worn.
TEMPERATURE CONTROLLER
ADJUSTMENT AND SERVICE – SEE
FIGURE 5
Proper operation and adjustment of the
temperature controller is vital to the proper
functioning of your Pick heater. A faulty or
incorrectly calibrated controller can cause
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