Bray Series 768 SlurryShield Bidirectional Wafer Slurry Valve

Heavy-duty sleeved wafer valve for mining and process slurries

The Bray Series 768 SlurryShield is a bidirectional slurry valve in a two-piece bolted wafer body of ductile iron, covering NPS 2 to 24 (DN 50 to 600). Twin elastomer sleeves with an encapsulated J-ring and a push-through gate give zero leakage in both directions and a self-cleaning action that prevents build-up, and the full-port design leaves an unobstructed flow path that extends sleeve life and keeps pressure drop low.

Mining is the lead application in the brochure: primary and secondary milling, primary and secondary cyclones, thickeners, filter pumps and presses, process water and tailings, as well as HPAL and POX autoclave and process pumps, power, chemical and pulp and paper. The wafer body fits between existing pipe flanges, which is convenient in tight pump-house pipework.

Technical specifications

Source: Bray brochure EN_V-6010_S768 and datasheet EN_SDS_768. MSS SP-81 and MSS SP-151 do not apply to this sleeved valve type, as printed by Bray.

Protection, flush plate and sleeve options

Upper and lower protective stem covers are standard on all models and increase cycle life in dirty or dusty environments. An optional bottom flush plate with tapped ports allows safe discharge and a flush-water connection. The gate can be specified in a range of corrosion-resistant alloys, and the pressure rating rises from 150 to 232 psi when a 2205 duplex gate is used in sizes up to NPS 18.

Sleeve options printed by Bray are natural rubber, Buna-N and EPDM, each with its own temperature window, so the choice should follow the process medium and temperature. Bray cautions that EPDM exposed continuously to elevated temperature ages prematurely and that frozen media must not be cycled.

768 compared with the other sleeved valves

The 768 is the general wafer choice for NPS 2 to 24. If the line is NPS 2 to 12 at 90 psi, the compact 765 is lighter. If the application needs flanged ends or sizes beyond 24 inches, use the 762, and for pressures above 232 psi use the 767. A handwheel, bevel gear, pneumatic, hydraulic or electric operator can be supplied, with the linear position sensor Bray lists for pneumatic knife gate actuators where continuous feedback is wanted.

How the Bray Series 768 works

The valve has a body that fits between two pipe flanges and a gate that moves across the flow. Two rubber sleeves sit on each side of the gate. When the gate closes, the sleeves press against it and seal in both directions. The gate pushes the solids out of the way as it moves, so the seal stays clean.

Where the Series 768 is used

• Milling circuits and cyclones
• Thickeners and filter presses
• Tailings and process water lines
• Autoclave and process pumps
• Chemical, power and pulp and paper plants

Selection checklist for the Series 768

• Size from NPS 2 to 24
• Pressure rating for the gate material
• Sleeve material for the temperature
• Gate alloy for wear and corrosion
• Actuator type
• Flush plate need
• Flange drilling
• Slurry solids and flow direction

Installation, commissioning and maintenance notes for the Series 768

Fit the valve between flanges with the gate free to move. Tighten the bolts evenly. Cycle the valve a few times before the slurry is started. Check the stem covers for damage. Replace the sleeves when the leakage rises.

Requesting a quotation for the Bray Series 768

Please send the size, the gate material, the sleeve type and the quantity. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.

Series 768 size range

The valve is made in sizes from NPS 2 to 24, which is DN 50 to 600.

Series 768 body

The body is ductile iron in two bolted pieces, in wafer style.

Series 768 pressure with a 316 gate

The rating is 150 psi for NPS 2 to 16 and 90 psi for NPS 18 to 24.

Series 768 pressure with a duplex gate

The rating is 232 psi for NPS 2 to 18 and 150 psi for NPS 20 to 24.

Series 768 sleeve temperature

Natural rubber works from minus 51 to 74 degrees C, Buna-N from minus 36 to 90, and EPDM from minus 54 to 120.

Series 768 gate options

Gates come in 304, 317, SAF 2507 duplex, 17-4PH, Hastelloy C, Monel and titanium.

Series 768 body options

The body can be ductile iron or CF3M stainless steel.

Series 768 drilling

The drilling follows ASME B16.5 Class 150.

Valve records for the Series 768

Record the sleeve type, the gate alloy and the date of each sleeve change.

Choosing the right Series 768 sleeve

Choose the sleeve by the slurry temperature and the chemicals in the line.

Documents and quotation

The brochure is attached as the datasheet; the Bray page also carries the operation and maintenance manual and a recommended specification. Please confirm slurry density, particle size, temperature, pressure, drilling, gate alloy and operator before requesting a price.

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