Standard Components
Operation
The Pressure Reducing Automatic Control Valve (ACV) with Low
Flow By-Pass is designed to automatically reduce a fluctuating higher
upstream pressure to a constant lower downstream pressure regard-
less of varying flow rates. It is controlled by a normally open, pressure
reducing pilot designed to: 1) Open (allowing fluid out of the main valve
cover chamber) when downstream pressure is below the adjust-
able setpoint, and 2) Close (allowing fluid to fill the main valve cover
chamber) when downstream pressure is above the adjustable setpoint.
A decrease in downstream pressure causes the valve to modulate
toward an open position, raising downstream pressure. An increase in
downstream pressure causes the valve to modulate toward a closed
position, lowering downstream pressure.
A Low Flow By-Pass Valve is piped parallel to the Main Pressure Re-
ducing Valve, and is set approximately
10 PSI higher.
The Low Flow
By-Pass handles flow requirements below the range of the Main Pres-
sure Reducing Valve. During "off peak" demand conditions, the Low
Flow By-Pass provides flow and pressure to the downstream zone. As
flow requirements increase beyond the capacity of the Low Flow By-
Pass, downstream pressure falls below the setpoint of the Main Pres-
sure Reducing Valve allowing it to throttle toward open, supplement-
ing flow and pressure. As flow requirements decrease, downstream
pressure rises above the setpoint of the Main Pressure Reducing Valve,
causing it to throttle toward closed, allowing the Low Flow By-Pass to
resume command of flow and pressure.
1
X
X
X
Y/FC
P/L
2
4
3
CLOSES VALVE
OPENS VALVE
FLOW
AOS
Start-up of an automatic control valve requires that proper procedures be followed. Time must be allowed for the valve to react to adjustments
and the system to stabilize. The objective is to bring the valve into service in a controlled manner to protect the system from damaging over-
pressure.
1. Prior to installation, flush line to remove debris.
2. Install valve so the flow arrow matches flow through the line, and gauges to monitor valve inlet and outlet pressures. A Position Indicator
can be installed to provide visual indication of valve position and operation without disassembly.
3. Install isolation valves upstream and downstream of the main valve.
4. Open the isolation ball valves in the control tubing if so equipped. Failure to open these will prevent the valve from functioning properly.
5. Install pressure gauges at locations upstream and downstream of the valve.
Note:
If using butterfly valves, ensure valve disc does not contact the main valve.
6. Provide adequate clearance for valve servicing and maintenance. Refer to valve servicing dimensions on next page.
7. Avoid installing valves 6" and larger in the vertical position (main valve stem horizontal). Automatic Control Valves (ACVs) are designed for
horizontal in-line installation, with the cover facing up (main valve stem vertical). Slow operation or premature stem and guide wear may
occur if valve is not installed according to factory recommendations. Consult factory for detailed engineering review prior to ordering if valve
is to be installed other than horizontally in-line.
8. If valve is equipped with a pilot control system, extra precautions should be made during installation to protect the piping circuit from dam-
age. Only remove the pilot control system from the valve if necessary. Tubing and fittings should be kept clean and replaced exactly as
removed. Consult appropriate hydraulic schematic to ensure proper re-assembly.
9. After installation, vent entrapped air from valve cover and pilot system by following instructions on Technical Bulletin.
1 – Main Valve (M100 – Single Chamber)
2 – Pressure Reducing Control
3 – Fixed Orifice
4 – Low Flow By-Pass
X – Isolation Cocks
Installation
LFM115-74 (Globe) Pressure Reducing Control Valve with Low
Flow By-Pass
2 IOM-ACV-115-74_6115-74 2115
EDP# 1917043
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