Cashco P3 - Manual (Page 2)

IOM-P3 2
SECTION IV
IV. STARTUP
SECTION V
V. SHUTDOWN
SECTION III
III. PRINCIPLE OF OPERATION
1. Movement occurs as pressure variations reg-
ister on the diaphragms (7.1). The registering
pres sure is the outlet, P
2
, or downstream pres-
sure. The range springs (15) oppose move ment
of the di a phragms. As outlet pressure drops,
the range springs push the di a phragms down,
open ing the ports; as outlet pres sure in creas es,
the di a phragms push up and the ports close.
2. A complete diaphragm failure will cause the reg u-
la tor to fail open.
The maximum outlet pressure is stamped on the
body as the upper range spring pres sure level, and
is the rec om mend ed “upper operative limit” for the
sens ing diaphragms (see Sec tion IV. Startup, Step
7). Higher press ures could dam age the diaphragms.
(Field hydro static tests fre quent ly de stroy di a -
phragms. DO NOT HYDRO STATIC TEST THRU AN
IN STALLED UNIT; ISO LATE FROM TEST.)
CAUTION
1. Start with the block valves closed. A by pass
valve may be used to maintain out let pres sure
in the down stream sys tem without changing the
fol low ing steps.
2. Relax 2nd stage range spring (15) by turning knob
(4) counter clockwise (CCW) until ro ta tion comes
to a complete stop.
3. If it is a “hot” piping system, and equipped with
a bypass valve, slowly open the bypass valve
to preheat the system piping and to allow slow
ex pan sion of the piping. Closely monitor outlet
(down stream) pres sure via gauge to ensure not
over-pressurizing. NOTE: If no bypass valve is
in stalled, extra caution should be used in starting
up a cold system; i.e. do everything slowly.
4. Crack open the outlet (downstream) block valve.
5. Slowly open the inlet (upstream) block valve ob-
serv ing the outlet (downstream) pressure gauge.
De ter mine if the regulator is fl owing. If not, slowly
rotate knob (4) clock wise (CW) until fl ow begins.
6. Continue to slowly open the inlet (upstream) block
valve until fully open.
7. Continue to slowly open the outlet (downstream)
block valve, especially when the downstream pip-
ing system isn't pressurized. If the outlet (down-
stream) pressure exceeds the desired pres sure,
close the block valve and go to Step 2, then return
to Step 4.
8. When fl ow is established steady enough that the
outlet (downstream) block valve is fully open, be-
gin to slowly close the bypass valve if installed.
9. Develop system fl ow to a level near its expected
normal rate, and reset the regulator set point by
turning knob (4) CW to increase outlet pressure,
or CCW to reduce outlet pressure.
10. Reduce system fl ow to a minimum level and
ob serve set point. Outlet pressure will rise from
the set point of Step 9. The maximum rise in
outlet pressure on decreasing fl ow should not
exceed the stated up per limit of the range spring
by greater than 10%. Example with 2-100 psig
(.14-6.9 Barg) range spring at low fl ow the outlet
pressure should not exceed 110 psig (7.6 Barg),
if it does, con sult factory.
Do not walk away and leave a bypassed
regulator unattended.
CAUTION
1. On systems with a bypass valve, and where sys-
tem pressure is to be main tained as the reg u la tor
is shut down, slowly open the bypass valve while
closing the inlet (up stream) block valve. Fully
close the inlet (up stream) block valve. (When on
bypass, the sys tem pres sure must be con stant ly
observed and man u al ly reg u lat ed. Close the
outlet (down stream) block valve.
2. If the regulator and system are to both be shut
down, slowly close the inlet (upstream) block
valve. Close the outlet (downstream) valve only
if reg u la tor re mov al is required.