Bray Series 765 Bidirectional Wafer Slurry Valve, NPS 2-12

A compact wafer slurry valve for small and medium lines

The Bray Series 765 is a bidirectional slurry valve in a compact two-piece bolted wafer body of ductile iron. Twin elastomer seats, in the form of metal-reinforced sleeves, and a push-through gate make it self-cleaning, so media does not build up in the seat area. It covers NPS 2 to 12 (DN 50 to 300) at 90 psi (6.2 bar), which suits process-water, tailings and sludge lines that do not need the pressure or size of the flanged 762.

With the valve fully open the bore offers no resistance to the line media, and the energized sleeves shield all metal components from the flow. A secondary wiper seal extends gate life and stops discharge from the top of the valve, and a drain plate with tapped purge ports is standard, giving safe discharge of media and an easy flush-water connection.

Technical specifications

Source: Bray brochure EN_V-6003_S765 dated 2022-02-04 and the Series 765 operation and maintenance manual.

Dimensions, weights and installation notes

Bray prints the face-to-face as an installed dimension and advises adding 6 to 13 mm (1/4 to 1/2 inch) for ease of installation. Operators are a direct-mounted handwheel as standard for NPS 2 to 10 and a bevel gear for NPS 12, with pneumatic, hydraulic and electric actuators available. Approximate weights from the brochure are below.

Maintenance and choosing a different series

The operation and maintenance manual covers unpacking, storage, installation, commissioning, lubrication through the grease port, secondary seal replacement and seat replacement for the valve with no retainer. Bray also states that dimensions are approximate and that certified drawings should be requested for piping layout.

If the line is larger than NPS 12 or the duty is above 90 psi, move to the 768 wafer or 762 flanged valve. For urethane-lined bores in abrasive service, see the Series 755.

How the Bray Series 765 works

The Series 765 is a knife-gate style valve. A flat gate moves up and down through the body. When the gate is down, it pushes through the flow and closes against twin rubber sleeves, which seal in both directions. When the gate is up, the bore is clear, so the slurry flows straight through with no obstruction. The sleeves shield the metal parts of the body from the slurry, and the push-through action clears solids from the seat area at each stroke. A wiper seal cleans the gate as it rises.

Where the Series 765 is used

• Process-water lines carrying solids
• Tailings and sludge lines
• Mining and mineral processing plants
• Wastewater plants
• Pulp and paper lines with fibre stock

Selection checklist for the Series 765

• Line size from NPS 2 to 12 (DN 50 to 300)
• Working pressure up to 90 psi (6.2 bar)
• Slurry type, solids content and abrasion
• Sleeve: natural rubber or EPDM, with the temperature range of each
• Gate material, 304 or a higher alloy for corrosive slurry
• Operator: handwheel, bevel gear, pneumatic, hydraulic or electric
• Flange drilling of ASME B16.5 Class 150 or other
• Space for the face-to-face length, plus 6 to 13 mm for fitting

Installation, commissioning and maintenance notes

Fit the valve between two flanges with the bolts tightened evenly. Support the pipe so the valve does not carry its weight. Connect flush water to the tapped ports in the drain plate if the slurry tends to pack. Operate the valve through its full stroke during commissioning. Check the wiper, the sleeves and the stem protection at set intervals, and replace worn sleeves before they leak.

Requesting a quotation for the Bray Series 765

Please send the size, the slurry, the pressure, the temperature and the operator type. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.

Series 765 materials

The standard body is ductile iron, the gate is 304 and the stem is 304. The wiper is EPDM on a carbon steel support.

Series 765 gate options

Gate options include 316, 317, SAF 2507 and 2205 duplex, 17-4PH, Hastelloy C and Monel.

Series 765 temperature range

Natural rubber seats work from -51 to 74 degrees C. EPDM seats work from -54 to 120 degrees C.

Series 765 fittings

A drain plate with tapped purge ports, a rod boot and upper stem protection are standard.

Valve records for Series 765

Keep the size, the sleeve material and the date of the last sleeve change with the plant list.

Choosing the right Series 765 operator

A handwheel is the simplest choice for valves that are operated seldom and are within reach. A bevel gear is used for NPS 12. For remote or automatic duty, pneumatic, hydraulic or electric actuators can be fitted, and the supply of air, oil or power then decides the choice. Check the stroke time against the process, because a fast closing gate can cause pressure surges in a long slurry line.

Series 765 compared with the flanged Series 762

The Series 765 is the compact wafer type for NPS 2 to 12 at 90 psi. The flanged 762 is meant for larger sizes and higher pressure.

Documents and quotation

The brochure and operation manual are listed on the Bray page; the brochure is attached. Confirm slurry type, temperature, particle size, drilling, operator and supply before ordering.

See the wider range of control and isolation valves on our catalogue, or send the model name and order number for a quotation.