2
IOM-8310HP-DIFF
SECTION III
III. PRINCIPLE OF OPERATION
1. The Differential Model 8310HP is available in two
options: 8310HP-1+6 is single diaphragm con struc tion;
8310HP-1+8 is double diaphragm con struc tion. The
dou ble diaphragm construction prevents the loading
fluid from direct mixing with the system fluid in case of
di a phragm failure.
2. Plug movement occurs as pressure variations register
on the diaphragm. One pressure is the outlet (p
2
)
or down stream pressure, which registers on the
“un der neath” side of the diaphragm. The second
pressure reg is tered is the loading (P
Load
) pres sure in
the spring chamber “above” the di a phragm. The range
spring determines the differential pres sure level (P
Set
).
As outlet (P
2
) pressure drops, the range spring with
P
Load
pressure pushes the diaphragm down, open ing the
port; as outlet (P
2
) pressure in creas es, the diaphragm
is pushed up and the port closes. As the loading (P
Load
)
pressure varies, the outlet (P
2
) pressure tends to follow.
An increase in P
Load
(
∆
P
Load
) will increase outlet P
2
pressure by near ly an equal amount (
∆
P
Load
=
∆
P
2
); a
decrease in P
Load
will have a similar effect on outlet P
2
pres sure.
3. For the 8310HP-1+6 (single diaphragm) design, a
com plete diaphragm failure will cause the fluids to
mix in the spring chamber or loading pressure piping
system.
4. For the 8310HP-1+8 (double diaphragm) design, a
complete diaphragm failure will cause the reg u la tor to
fail open, leaking fluid through the annular ring vent
hole.
NOTE:
Composition (soft) diaphragms may be
utilized only on -1+6 single diaphragm con struc tion.
IV. START-UP
1. Start with the block valves closed. A bypass valve may
be used to maintain outlet pressure in the down stream
system without chang ing the fol low ing steps.
2. Remove the closing cap and relax the range spring
by turning the adjusting screw counter clockwise
(CCW) (viewed from above) a min i mum of three (3)
full revolutions. This re duc es the outlet (downstream)
pres sure set point.
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. Ensure proper steam trap operation, if installed.
Close ly 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.
the regulator is flowing. If not, slowly rotate the regulator
adjusting screw clock wise (CW) (viewed from above)
until flow be gins.
6. Continue to slowly open the inlet (up stream) block valve
until fully open.
7. Continue to slowly open the outlet (downstream) block
valve, especially when the downstream piping sys tem
isn’t pressurized. If the outlet (down stream) pressure
exceeds the de sired pres sure, close the block valve
and go to Step 2, then return to Step 4.
8. When flow is established steady enough that the outlet
(downstream) block valve is fully open, begin to slowly
close the bypass valve, if in stalled.
NOTE:
The needle
valve (39) is shipped in a full open position. If the system
is unstable due to pressure fluctuations, slowly close
the needle valve (39) until the system becomes stable.
This needle valve should never be in a fully closed
position.
9. Set the regulator set point (P
set
) by turning the ad just ing
screw clockwise (CW) to increase outlet pres sure or
CCW to reduce outlet pressure. The outlet (P
2
) pressure
under these conditions will approximate the desired
dif fer en tial pressure when loaded with P
Load
.
13. Model 8310HP 1+6 - refer to Figure 1; for 8310HP 1+8
refer to Figure 2. Regulator may be rotated around the
pipe axis 360°. Rec om mend ed position is with spring
chamber ver ti cal upwards. Orient such that the spring
chamber vent hole does not collect rainwater or debris.
SECTION IV
Do not walk away and leave a bypassed regulator
un at tend ed!
CAUTION
14. Regulators are not to be direct buried un der ground.
15. For insulated piping systems, recommendation is to not
insulate regulator.
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
