Cashco HP - Manual (Page 2)

IOM-HP 2
SECTION III
* NOTE: Systems sequencing operations at startup,
normal operation, failure mode(s), and shutdown must as-
sure that the pressure (P
Load
) on the spring chamber
does not exceed the pressure registering on the wetted
side of the diaphragm. Should this "pressure reversal" oc-
cur, particularly to metal diaphragms, the diaphragm may
be permanently damaged and cause improper operation.
P
1
> P
2
> P
Load
Pressure reversal is normally caused by the inlet pressure
to a regulator being interrupted (automatically or manually).
IV. STARTUP
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 the range spring by turning the adjusting screw
counter clockwise (CCW) a minimum of three (3) full
revolutions. This reduces the outlet (down stream) pres-
sure set point.
3. If it is a “hot” piping system, and equipped with a by-
pass valve, slowly open the bypass valve to pre-heat
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.
SECTION V
V. SHUTDOWN
1. On systems with a bypass valve, and where sys tem
pressure is to be maintained 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
(upstream) block valve. (When on bypass, the system
pressure must be constantly observed and manually
regulated. Close the outlet (downstream) 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.
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 the regulator
adjusting screw clockwise (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 nor-
mal rate, and reset the regulator set point by turning
the adjusting screw 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 upper limit of the
range spring by greater than 10%; i.e. 400–750 psig
(27.5 –51.7 Barg) range spring, at low fl ow the outlet
pressure should not exceed 825 psig (56.8 Barg), if it
does, consult factory.
III. PRINCIPLE OF OPERATION
1. Movement occurs as pressure variations register on
the diaphragm. The registering pressure is the outlet,
P
2
, or downstream pressure. The range spring op-
poses di a phragm movement. As outlet pressure drops,
the range spring pushes the dia phragm down, opening
the port; as outlet pres sure in creas es, the diaphragm
pushes up and the port opening closes.
2. A complete diaphragm failure will cause the reg u la tor
to fail open.
SECTION IV
CAUTION
The maximum outlet pressure is list ed on the name-
plate as the upper range spring pres sure level, and
is the rec om mend ed "upper operative limit" for
the sens ing diaphragm. Higher press ures could
dam age the di a phragm. Refer to HP-TB, Table 5,
for “emergency over-pressure level”. NOTE: Inlet
pres sure and outlet pressure ratings are at different
levels. (Field hydro static tests fre quent ly de stroy
dia phragms. DO NOT HYDRO STATIC TEST THRU
AN IN STALLED UNIT; ISO LATE FROM TEST.).
CAUTION
Do not walk away and leave a bypassed reg u la tor
unattended.