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Standard Components

Operation

The Combination Backpressure or Sustaining ACV with Hydraulic 
Check Feature is designed to permit flow when upstream pressure is 
above the adjustable setpoint of the control pilot, and throttle toward 
closed when upstream pressure falls below the adjustable setpoint, 
and close drip-tight when downstream pressure becomes greater 
than upstream pressure.
It is controlled by a normally closed control pilot designed to: 1) Open 
(allowing fluid out of the main valve cover chamber) when upstream 
pressure is above the adjustable setpoint, and, 2) Close (allowing 
fluid to fill the main valve cover chamber) when upstream pressure 
is below the adjustable setpoint. An increase in upstream pressure 
causes the valve to modulate toward an open position. A decrease 
in upstream pressure causes the valve to modulate toward a closed 
position.
If downstream pressure becomes greater than upstream pressure, 
downstream pressure is admitted to the main valve cover chamber, 
closing the valve and preventing reversal of flow. Normal backpres-
sure or sustaining operation resumes when upstream pressure ex-
ceeds downstream pressure.
When the valve is installed “in line” on the discharge of a pump, it acts 
as Backpressure Control Valve. When pump discharge pressure falls 
below the pilot setting, the valve modulates toward a closed posi-
tion, increasing backpressure against the pump. The valve should be 
specified to include the optional opening speed control when used for 
Backpressure applications.

When the Model valve is located "in line" connecting two distribution 
zones, the valve acts as a Pressure Sustaining Control Valve. When 
pressure in the upstream zone falls below the pilot setting, the valve 
modulates toward a closed position, sustaining pressure in the 
upstream zone. The valve will close, if necessary, until upstream 
pressure is above the pilot setting. The valve should be specified to 
include the optional opening speed control and position indicator 
when used for Pressure Sustaining applications.

1

X

X

X

Y/FC

4

4

2

P/L

CLOSES VALVE

OPENS VALVE

FLOW

(AOS)

3

1.  Clear the line free of slag and other debris.

2.  Install the valve so that the FLOW ARROW marked on the valve body/tag corresponds to flow through the line.

3.  Close upstream and downstream isolation valves.

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 a pressure gauge at a location upstream of the valve.

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 – Main Valve (M100 – Single Chamber) 

2 – Pressure Sustaining Control 

3 – Adjustable Closing Speed

4 – Check Valve

X – Isolation Cocks

Installation

LFM116-5 (Globe) Pressure Sustaining Control Valve with 
Hydraulic Check Feature

2          IOM-ACV-116-5_6116-5 2115 

EDP# 1917051 

© 2021 Watts

Summary of Contents for LFM116-5

Page 1: ...2 Setting the Pressure Controls 3 Maintenance Schedule 6 Trouble Shooting Guide 6 Valve Disassembly Instructions 8 ACV Schematic 11 Local building or plumbing codes may require modifica tions to the information provided You are required to consult the local building and plumbing codes prior to installation If the information provided here is not consistent with local building or plumbing codes the...

Page 2: ...nclude the optional opening speed control when used for Backpressure applications When the Model valve is located in line connecting two distribution zones the valve acts as a Pressure Sustaining Control Valve When pressure in the upstream zone falls below the pilot setting the valve modulates toward a closed position sustaining pressure in the upstream zone The valve will close if necessary until...

Page 3: ... to 21 2 turns from full closed position STEP 2 To ensure proper operation any trapped air will need to be bled off the valve cover during startup If your ACV includes a bleed valve use a flat head screwdriver to slowly open the valve See Figure 1 If your valve does not include a bleed valve bleed air by loosening a fitting on the valve or a plug at the highest point of the valve as sembly STEP 3 ...

Page 4: ...and close the up stream isolation valve until the inlet pressure drops to the desired setting STEP 7 Adjust the Sustaining Control screw IN clockwise until the inlet pressure begins to increase or OUT counterclockwise to de crease stopping at the desired pressure See Figure 2 4 IOM ACV 116 5_6116 5 2115 EDP 1917051 2021 Watts Figure 2 PV20C Pressure Sustaining Control Clockwise to increase inlet p...

Page 5: ...sing IF INSTALLED Opening Speed Flow Control Adjustment The Opening speed flow control allows free flow into the cover and re stricted flow out of the cover of the main valve If recovery of pres sure is slow upon increased downstream demand turn the adjust ment screw OUT counterclockwise increasing the rate of open ing IF recovery of downstream pressure is too quick as indicated in a rapid increas...

Page 6: ...e specification sheets for approximate cover capacity A continuous flow of water from the open port indicates a damaged diaphragm or loose disc diaphragm assembly Disassemble valve and replace diaphragm or tighten disc diaphragm assembly Test 2 Seat Seal Test 1 Close downstream isolation valve and install pressure gauges on an open inlet and outlet port of main valve 2 Open upstream isolation valv...

Page 7: ...mbly by partially opening from full closed position Improperly configured opening speed control if equipped Adjust opening speed control to verify functionality adjust as required Standard setting for opening speed control is 11 2 21 2 turns open from full closed position Can be adjusted in field Main Valve will not close Closed isolation valves in pilot system Check isolation valves ensure open D...

Page 8: ... Remove cover nuts and washers 3 Remove the cover If cover is not free to be removed loosen it by tapping upward along its outside edge with a dull cold chisel pic tured above a Large valves may require the installation of lifting eye bolts in order to facilitate cover removal installation ports are provided on the cover for this purpose 4 Remove the Disc and Diaphragm Assembly from the valve body...

Page 9: ... brush or by using a Mineral Dissolving Solution Inspect parts for wear and replace if necessary 7 Inspect valve seat If seat is not damaged removal is not necessary Valve seats 6 and smaller are threaded into the body of the valve and require a seat removal tool Figure 4 Table 1 details the tool dimensions for seat removal Valve seats 8 and larger are held in the valve body with stainless steel c...

Page 10: ... Nuts in a crossing pattern to ensure even distribution Test the Disc and Diaphragm Assembly for smooth travel by following the Freedom of Movement Test procedure in previous section 11 Test the integrity of the Seat Seal by following the Seat Seal Test procedure in previous section 12 Return valve to service by following instructions on the Technical Bulletin matching the valve function Size in 1...

Page 11: ...l 9 Stem Washer ASTM A276 304 Stainless Steel 10 Diaphragm Washer ASTM A536 65 45 12 Epoxy Coated Ductile Iron 11 Diaphragm Buna N Nitrile 12 Disc Retainer ASTM A536 65 45 12 Epoxy Coated Ductile Iron 13 Seat Disc Buna N Nitrile 14 Spacer Washer x5 NY300 Fiber 15 Disc Guide ASTM A743 CF8M 316 Stainless Steel 16 Shaft ASTM A276 304 Stainless Steel 17 Seat Ring ASTM A743 CF8M 316 Stainless Steel 17A...

Page 12: ...ot be responsible for any incidental special or consequential damages including without limitation lost profits or the cost of repairing or replacing other property which is damaged if this product does not work properly other costs resulting from labor charges delays vandalism negligence fouling caused by foreign material damage from adverse water conditions chemical or any other circumstances ov...

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