cashco 988 Panduan Pemasangan, Pengoperasian & Pemeliharaan - Halaman 3
Jelajahi secara online atau unduh pdf Panduan Pemasangan, Pengoperasian & Pemeliharaan untuk Unit Kontrol cashco 988. cashco 988 20 halaman. Globe-style pneumatic control valve body
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Figure 2: Body Insulation
IV. STARTUP
A. General:
1.
Ensure that the Model 988/989 unit has been
prop er ly ad just ed and calibrated, including the
positioner if in stalled.
2.
Recommend startup to be in a "manual" mode.
This pro ce dure assumes double block (iso la tion)
and bypass valves for the "control valve sta tion".
See Figure 1.
3.
Start with either of the two block valves closed,
with the oth er open. The bypass valve should be
closed. Pressurize sys tem if possible/practical.
4.
Back out the airset's adjusting screw until loose.
5.
Turn on air supply pressure.
6.
Adjust the air supply airset (filter-regulator) to the
prop er lev el as indicated as follows:
Bench Setting
psig
5–15
(.34–1.0)
15–60
7.
Place loop controller into "manual" mode. Vary
set ting from minimum – mid-range – max i mum
SIG out put. Observe re sponse of con trol valve unit
to these chang es of in put SIG. The valve should
fully stroke at the vari a tion from min i mum SIG to
max i mum SIG; the mid-range SIG should have the
valve stem at/near 1/2 travel.
DO NOT WALK AWAY AND LEAVE A MANUALLY
CON TROLLED CONTROL VALVE UNATTENDED!
IOM-988/989-BODY
Airset Output
(Barg)
psig
(Barg)
20
(1.4)
(1.0–4.1)
75
(5.2)
CAUTION
outlet) should be supported and guid ed to ensure
unidirectional expansion/contraction.
C. Removal From Piping System:
1.
Care should be taken in removal of separable
flanged units. Run wire across the flange face
and through bolt holes in 180° crossing pattern to
prevent flanges from coming loose during handling.
Exhibit care in handling flanged units to prevent sep a ra ble
flang es from coming loose, falling to floor and smashing
feet/toes.
SECTION IV
8.
Confirm that action of controller and positioner
– direct or reverse – are pro duc ing the desired
re sponse in the con trol unit. Confirm that the control
valve "fail" po si tion is as required.
9.
Hereafter, the procedure assumes that actual
flu id flow may be established. This may not be
prac ti cal/pos si ble in all cas es; if so, vary procedure
as re quired. Always "heat" or "cool" down the
system piping SLOW LY by open ing the control
valve sta tion by pass 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 by pass valve and vary flow rate
man u al ly to observe the response of the con trol ler
and control valve unit to geth er.
11. Attempt to develop manual control of the loop by
open ing/closing the manual bypass as re quired,
or by manually con trol ling mainstream flow as
re quired.
12. When the control valve is partially open, slowly crack
open the closed block valve while si mul ta neous ly
closing the bypass valve. Continue this pro ce dure
until the bypass is closed and the block valves are
both fully open. The system is still un der "man u al"
mode control, but all flow is pass ing through the
control valve.
13. Vary controller "manual" SIG output until match ing
the "au to mat ic" SIG output, then change the mode
of the controller over to "automatic". The loop will
ex pe ri ence a minimum of upset conditions, and will
be in au to matic control.
CAUTION
3