Cashco DA1 - Manual (Page 2)

IOM-DA1 2
which allows the diaphragm chamber to
always be self draining. The external sensing
line may be sloped upward for liquids or gases.
CAUTION B
DO NOT HYDROSTATIC TEST THROUGH AN
INSTALLED UNIT; ISOLATE REGULATOR
FROM TEST. The upper range spring pres sure
level on the nameplate is the rec om mend ed “up-
per operating limit” for the sens ing diaphragm.
Higher pres sures could cause internal dam age.
In ad di tion, note on the nameplate that the Inlet
and Outlet pres sure and tem per a ture ratings
are at different levels.
Recommended Piping Schematic
For Pressure Reducing Station
IV. PRINCIPLE OF OPERATION
1. Movement occurs as pressure variations register
on the diaphragm. The registering pressure is the
outlet, P2, or downstream pressure. The range
spring op pos es di a phragm movement. As outlet
pressure drops, the range spring pushes the di a-
phragm down, opening the port; as outlet pres sure
V. STARTUP
1. Start with the block valves closed.
2. Relax the range spring by turning the ad just ing
screw CCW (viewed from above) a minimum of
three (3) full rev o lu tions. This reduces the outlet
(down stream) pres sure set point.
3. If it is a “hot” piping system, and equipped with
a bypass valve, partially open the bypass valve
to pre heat the system piping and to allow slow
ex pan sion of the piping. Ensure proper steam
trap operation if installed. Closely monitor outlet
(down stream) pressure via gauge to ensure not
over-pres sur iz ing. 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 to
about 25% open, observing the outlet (down-
stream) pres sure gauge. Determine if the reg u -
la tor is fl owing. If not, slowly rotate the regulator
ad just ing screw CW (viewed from above) until fl ow
be gins.
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 inlet block valve and go to Step 2. Close
bypass valve approximately 25%, and re peat pro-
ce dure.
8. When fl ow is established steady enough that the
outlet (downstream) block valve is fully open, begin
to slowly close the bypass valve if installed.
increases, the diaphragm pushes up and the port
opening closes.
2. A complete diaphragm failure will cause the reg u-
la tor to fail open and fl uid will discharge from the
spring chamber vent hole.
SECTION IV
SECTION V
CAUTION D
Do not walk away and leave a bypassed reg u -
la tor unattended!
Supply
@ P1
Model DA1
Reducing
Regulator
SRV
P1
Outlet
@ P2
Bypass
Blowdown-
Drain
Blowdown-
Drain
(Shaded portion for steam/condensate systems)
TR TR
CAUTION C
Installation of adequate overpressure pro tec tion
is recommended to pro tect the reg u la tor from
over pres sure and all down stream equip ment from
dam age in the event of regulator failure.