SOCLA BA 4760 Backflow Preventer

General Information

General

Designed to protect drinking water supply networks against the backflow of risk fluids up to category 4 according to NF EN1717. The device is designed to prevent any backflow of polluted water into the drinking water supply network as a result of back pressure or back siphonage when the pressure upstream of the device is lower than the pressure downstream of it.

Fields of Application

For systems liable to generate pollution risks:

• Sanitary networks: hospitals, laboratories, dialysis centres, water treatment.
• Technical networks: heating, air conditioning, irrigation, water dispensers.
• Fire suppression systems: sprinklers, fire hoses.
• Professional networks: industrial facilities, surface treatment, chemical industry, agrifood.
• Temporary networks: water supply for trade fair stands, festivals, exhibitions.

Note: The applications also depend on legislation in the country of use. Please contact your national authorities for further information.

Technical Specifications

Type of fluid: Clear water

Operation: Horizontal position

DN 65 to 250 mm, Connections: Drilled flanges

Maximum operating pressure: 10 bar (1 MPa)

Minimum inlet pressure: 1.5 bar (150 KPa)

Maximum operating temperature: 65°C

Standards - Approval

Conforms to the following standards: EN1717, EN12729

Approvals: ACS, NF, Kiwa, UNI, Kiwa UK-REG 4, BUREAU VERITAS, BELGAQUA

1. Operating Principle

1.1 Operating Principles

Normal Flow Conditions > Filling / Flow Start: The two check valves are opened. The relief valve is closed (closing pressure is lower than the upstream check valve opening pressure). Water is supplied to the downstream chamber.

No Flow Conditions > Flow Interruption: The two check valves are closed. The relief valve is closed (because the pressure required to close it is lower than the pressure required to open the upstream check valve).

1.2 Malfunctions

There can be no inversion or fluctuations of pressure between the intermediate chamber and the circuit upstream of the backflow preventer. The construction of the device in accordance with standards requires the upstream pressure to remain 140 mbar higher than the pressure in the intermediate chamber at all times. This differential value controls the opening of the relief valve and the drainage of the backflow preventer. Backflow preventers with verifiable reduced pressure zones self-protect against their own malfunctions. The device is made safe in static pressure situations.

The following situations can arise:

• Upstream Negative Pressure / Back-Siphonage: The two check valves close. The relief valve opens and drains the intermediate chamber.
• No Flow with Upstream Valve Defective: The upstream pressure increases the pressure in the intermediate chamber. The relief valve opens and causes a continuous discharge.
• Overpressure with Downstream Valve Sealed: If the check valve is perfectly sealed, no malfunction will occur: the valve remains closed.
• Overpressure with Downstream Check Valve Defective: The overpressure reaches the intermediate chamber causing the relief valve to open and discharge into the sewage network.

2. Installation Instructions

2.1 Installation

Before installing the BA backflow preventer, check that:

• The BA device must be easily accessible to allow inspection, maintenance and replacement of defective components.
• Test points must be provided to enable the system to be tested without difficulty.
• It must not be installed in areas subject to flooding.
• It must be installed in a ventilated area (non-polluted atmosphere).
• The relief system must be capable of discharging the relief flow.
• It must be protected against frost and extreme temperatures.
• It must be installed horizontally with the relief port facing down.
• The funnel, with air gap, must be connected to the relief network.
• It can only be used for potential backflow not exceeding the relief capacity.

The protection device must be installed by a qualified technician.

2.2 Commissioning

1. Flush and fully drain the upstream pipes before installing the BA protection device with its accessories.
2. Install the BA protection device with its accessories, in the direction of flow, as follows:
   
   • Upstream: one type SOCLA or equivalent Butterfly valve,
   • Between the upstream valve and the device: one type Socla Y333P or equivalent mesh strainer with drain cock.
   • Downstream: one type Socla or equivalent Butterfly valve.
3. Fit the funnel on the BA protection device. It is designed to be connected to a pipe (e.g. PVC discharge pipe) with external diameter equal to the diameter shown (see ØF).

2.3 Filling with Water

During filling with water:

• The upstream and downstream valves are closed.
• Open the upstream valve slowly, to bring the BA protection system up to pressure gradually.
• Open and close tap No. 1 and then taps 2 and 3 respectively to drain the BA protection device.
• Open the downstream valve slowly, to commission the BA protection system.

Once the BA protection system has been commissioned, it:

• Ensures that the downstream water requirement is met.
• Protects the upstream network against the risk of pollution.

Precautions

• In the case of an upstream diversion in the area right in front of the backflow preventer, it is necessary to install a check valve between the diversion and the backflow preventer.

3. Nomenclature and Sizing

Key

• 1 - Casing
• 2 - Outlet drain holder
• 3 - Hex head screw
• 4 - Union nut
• 5 - Draining valve seat
• 6 - Discharge valve spring
• 7 - Discharge valve
• 8 - Upstream check valve
• 9 - Retainer
• 10 - Draining valve stem
• 11 - Downstream check valve
• 12 - Membrane disc
• 13 - Safety seal
• 14 - Draining valve head
• 15 - Draining valve seat and cover
• 16 - Cover
• 17 - Test cock chain
• 18 - Protective head
• 19 - Eye bolt
• 20 - Screw
• 21 - Test cock M 1/2" Gas
• 22 - Draining valve head seal
• 23 - Membrane

3.1 Testing Kit

In accordance with national statutory regulations, BA backflow preventers must be regularly inspected (once a year in most countries) by an authorised maintenance technician. BA backflow preventers must undergo compulsory annual testing using test equipment conforming to NF P43-018, such as Socla ref. 2234900M2 or equivalent. This equipment must be checked at least once every two years.

3.2 Fitting / Removal Instructions

All components of the backflow preventer can be checked or replaced on site without removing the entire device.

• Stop the flow by closing the upstream and downstream stop valves.
• Drain the backflow preventer by opening the upstream test cock.
• Remove the screws (20) of the cover (16).
• Separate the cover (16) from the casing (1). If necessary, in case the cover gets stuck, insert any cover screw (20) into the additional hole of the cover until the cover is free.
• Take out the draining valve assembly A from the casing (1).

Remove the check valves:

• Remove the retainers (9) using pliers.
• Remove the 1st check valve (8): introduce a rod on the inlet side, and gently hit the check valve. Repeat the same operation for the 2nd check valve (9) (11).

Remove the relief valve seat:

The seat (5) of the draining valve is fitted in piston position on the bottom of the casing (1), take it out:

• By hands through the internal side of the body if possible.
• By pushing in direction of the body inside through the discharge hole using a screwdriver.

3.3 Refitting Instructions

CAUTION: during the assembly, Silicone grease will have to be applied on O-rings.

Replace the check valve

• Introduce the 1st check valve in its bore (8) (9). Then using a lever (bottom part placed in the relief valve bore) and a plastic wedge, push the subset to replace it.
• Important: take care that the relief valve seat is removed.
• With the same method, mount the second check valve.

Replace the relief Valve

• Mount the relief valve seat in its bore. If necessary, push it using a plastic rod.
• Place the relief valve spring on the seat (5).

Before the final operation, carefully dry the surfaces (body – cover) in contact with the membrane. If the membrane is assembled for a second time, apply talcum powder on it.

• On the working station, place the relief valve unit in the cover.
• Take care of the membrane orientation.
• Turn the subset and place the screws on the cover.
• Take the unit and carefully position the relief valve in the spring then in the seat.

IMPORTANT: angular movements have to be as smallest as possible. Tight the screws to the following torques: DN65 : 80 mN - DN80 : 90 mN - DN100 : 130 mN

Replace the outlet drain holder (2)

• The outlet drain holder is maintained on the casing by bolts and nuts. When replacing it, remove the screws from a groove on the casing.
• Then manually screw it until it reaches the draining valve (10).

Specification for DN200 and DN250:

• Dismantling of the upstream and downstream check valves: insert two screws into the upstream and downstream threaded (M10) in order to remove the upstream and downstream subset out of their own bore. Then remove them from the body.
• Reassembling of the new subset (upstream and downstream check valve): introduce the first subset in the body bore, then with a lever into the low part of the body (draining valve seat removed), push the subset to replace it.
• Remark: the upstream seat is equipped with an external notch with must be placed in the low part of the body. Do not forget to replace the two safety seals (13). Reassembling the draining valve seat (5) and the spring (6).

3.4 Repair Kits

Repair kits are available and make it possible to replace the specific defective part on the BA 4760 backflow preventer.

* Maximum torque for tightening bolts of the backflow preventer cover.

4. Troubleshooting

Guarantee

Watts products are thoroughly tested. The guarantee covers solely replacement or repair, free of charge, of components with proven manufacturing defects. The limitation period for claims is two years from delivery. This warranty excludes damage from normal usage, wear, or unauthorized repairs. For full details, see the Watts website. All sales are subject to Watts terms found on www.wattsindustries.com.