Cashco 2296HF - Manual (Page 3)

3 IOM-2296
3. Failure to remove moisture will cause corro-
sion to the internals of the actuator casings.
4. Connections for the air supply are 1/4" female
NPT. Use a suitable pipe thread sealant
when installing the pipe or tube fi tting. DO
NOT allow sealant to enter the tube/pipe.
C. Air Supply:
1. Use a desiccant dried, instrument quality air
supply. Such a supply is recommended for
outdoor installations, and is required in areas
of freezing weather conditions.
2. If air supply contains moisture and /or lubri-
cating oil, the air should be fi ltered with a
coalescing type of fi lter prior to use in stroking
the actuator.
SECTION IV
IV. STARTUP
A. General:
1. Ensure that the Model 2296 / 2296HF unit
has been properly adjusted and calibrated,
including the positioner if installed.
2. Recommend startup to be in a “manual” mode.
This procedure assumes double block (iso la-
tion) and bypass valves for the “control valve
station”. See Figure 1.
3. Start with either 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 as follows:
7. Place loop controller into “manual” mode. Vary
setting from minimum – mid-range – max i mum
SIG output. Observe response of con trol
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 the action of controller and positioner
– direct or reverse – are producing the de sired
response in the control unit. Con fi rm that the
control valve “fail” position is as re quired.
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
SLOWLY by opening the control valve station
bypass valve in small increments.
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, crack
open slowly the closed block valve while si mul-
ta neous ly closing the bypass valve. Con tin ue
this procedure until the bypass is closed and
the block valves are both fully open. The
system is still under “manual” mode control,
but all fl ow is passing thru 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.
Bench Setting Airset Output
psig (Barg) psig (Barg)
5–15 (.34–1.0) 20 (1.4)
15–60 (1.0–4.1) 75 (5.2)
CAUTION
DO NOT WALK AWAY AND LEAVE A MANUALLY
CONTROLLED CONTROL VALVE UNATTENDED!