Cashco Ranger QCT - Manual (Page 14)

IOM-Ranger 14
9. Hereafter, the procedure assumes that actual
fl uid fl ow may be established. This may not
be practical/possible in all cases; if so, vary
pro ce dure as required.
Always “heat” or “cool” down the system pip ing
SLOW LY by opening the control valve station
bypass valve in small in cre ments.
10. With one of the control valve station block
valves still closed, and the loop controller
still in “manual” mode, open bypass valve
and vary fl ow rate manually to observe the
re sponse of the controller and control valve
unit together.
11. Attempt to develop manual control of the loop
by opening/closing the manual bypass as re-
quired, or by manually controlling main stream
fl ow as required.
12. When the control valve is partially open, slow ly
crack open the closed block valve while si mul -
ta neous ly closing the bypass valve; it may be
necessary/desirable to vary the manual out put
SIG from the controller simultaneously also.
Continue this pro ce dure until the bypass is
closed and the block valves are both fully open.
The system is still under “manual” mode con-
trol, but all fl ow is passing through the control
valve.
13. Vary controller “manual” SIG output until
match ing the “automatic” SIG output, then
change the mode of the controller over to
“automatic”, and the loop will experience a
minimum of upset conditions, and will be in
automatic control.
SECTION V
WARNING
V. STARTUP
A. General:
1. Ensure that the Ranger QCT unit has been
properly adjusted and calibrated, including
the positioner if installed, per actuator main-
te nance manuals IOM-48 or 148.
2. Recommend startup to be in “manual” mode.
This procedure assumes double block (iso-
la tion) and bypass valves for the “control valve
station”. See Figure 1.
3. Start with one of the two block valves closed,
with the other open. The bypass valve should
be closed. Pressurize system if possible/
prac ti cal.
4. Back out the airset's adjusting screw until
loose.
5. Turn on air supply pressure.
6. Adjust the air supply airset (fi lter-regulator)
to the proper level as indicated on the unit's
nameplate (20), in IOM-48 or IOM-148, or
the tech ni cal bulletin Ranger-TB. DO NOT
STROKE THE CONTROL VALVE WITH
AN AIR SUPPLY PRES SURE SETTING
GREAT ER THAN REC OM MEND ED MAX I-
MUM PRESSURE!
7. Place loop controller into “manual” mode. Vary
setting from minimum – mid-range — maxi-
mum SIG output. Observe response of control
valve unit to these changes of input SIG. The
valve should fully stroke at the variation from
minimum SIG to maximum SIG; the mid-range
SIG should have the valve stem travel at/near
1/2 open.
8. Confi rm that action of controller and po si tion er
– direct or reverse – are producing the desired
response in the control unit. Confi rm that the
control valve “fail” position is as re quired.
DO NOT WALK AWAY AND LEAVE A MANUALLY
CONTROLLED CONTROL VALVE UN AT TEND ED!