Cashco HP Manuel d'utilisateur télécharger pdf (Page 2)

IOM-HP2

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

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,

, 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.

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Cashco HP Manuel d'utilisateur Page 2

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