Hydraulic Control Valves & Knife Gate Valves | Seal Pumps and Valves
A pump is only as good as the valve that isolates it. On slurry, sludge and waste water duty the valve is usually the part that fails first, because a conventional gate or butterfly valve leaves a seat full of solids to close onto. Knife gate valves are built for exactly that: a thin, sharp gate that cuts through the medium rather than pushing it aside.
Types we supply
- Wafer type knife gate valve — fits between flanges; the most compact option.
- Lugged type knife valve — tapped lugs allow dead-end service and easier removal.
- Flange type knife valve — full flanged body where a rigid connection is required.
Actuation can be manual, pneumatic or motorised, so the same body can serve a hand-operated isolation point or an automated line.
Materials and standards
- Stainless steel bodies and trim for corrosive and hygienic duties.
- WCB (cast carbon steel) for general service.
- Manufactured strictly to ISO, API, JIS and DIN standards.
- Seat and packing options to suit the medium.
Where they are used
- Isolation on the suction and discharge of slurry and sludge pumps.
- Waste water and sewage lines where rag and solids content defeats other valve types.
- Pulp and paper stock lines.
- Ash, sand and mineral handling.
- Process lines needing a full-bore, unobstructed flow path when open.
Selecting a knife gate valve — what to tell us
1. Line size and pressure rating. 2. Medium — solids content, particle size, abrasiveness, temperature. 3. Body and trim material — stainless or WCB, and any seat requirement. 4. Actuation — manual handwheel, pneumatic cylinder or electric actuator, and whether fail-open or fail-closed is needed. 5. Flange standard to match the pipework.
Frequently asked questions
Frequently asked questions
Why use a knife gate valve instead of a butterfly valve on slurry?
A butterfly valve leaves a disc and seat in the flow path, and solids pack behind the disc. A knife gate has a thin gate that cuts through the medium and, when open, leaves an almost unobstructed bore.
Which actuation options are available?
Manual, pneumatic and motorised. The same valve body can be supplied with any of them.
Are stainless steel bodies available?
Yes — stainless steel and WCB are both available, manufactured to ISO, API, JIS and DIN standards.
Can you supply valves to match an existing flange standard?
Yes. Wafer, lugged and flanged patterns are available; tell us the standard and pressure rating and we will match it.
Is the actuator supplied with the valve?
Yes — supplied as a complete actuated unit, with the actuator matched to the valve and the duty.
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Need help specifying hydraulic control valves?
Send us the pump make, model and serial number and we will come back to you.