DQ-Series Knife Gate Valves: Compact, Powerful Performance for Tough Media

When your process lines carry slurry, fibre and suspended solids, ordinary valves don’t last long. Blockages, leaks and high maintenance become the norm – and uptime suffers.

That’s why many South African plants are turning to the DQ-Series Knife Gate Valve, supplied and supported by KV Controls. With its compact body, strong cutting action and easy-maintenance design, the DQ-Series is built specifically for demanding, solids-rich applications.

In this article, we look at how the DQ-Series is built, where it’s used, and why it’s a smart choice for chemical plants, pulp and paper mills, wastewater plants and more.

Designed for Solids, Fibres and Slurries

The DQ-Series Knife Gate Valve is a linear shut-off valve with a lightweight, compact body that still offers high reliability under tough conditions.

You can configure it for your plant as:

• A manual valve with handwheel or gearbox for straightforward local operation

• An actuated valve with pneumatic cylinder or electric actuator for remote or automated control

The heart of the design is an arc-shaped gate that slices through fibre, pulp and suspended particles. Instead of trapping solids in the seat area, the gate cuts and clears the flow path, reducing the risk of clogging and ensuring consistent shut-off.

Practical Features That Reduce Downtime

Rather than just listing specs, it helps to see what these features actually mean in day-to-day operation:

Compact One-Piece Body

• A single-piece compact body reduces overall weight and footprint

• Easier to install in tight pipe racks and congested plant layouts

Shearing and Self-Cleaning Action

• The gate delivers strong shearing force on closing

• Built-in auto-cleaning effect helps keep the seat and gate surface clear of fibre and solids

• Less build-up means longer service intervals

Removable Seat for Fast Maintenance

• The seat can be removed and replaced without extensive disassembly

• That means quicker turnaround during shutdowns and lower life-cycle cost

Where the DQ-Series Knife Gate Valve Excels

The DQ-Series is positioned as a multi-industry solution wherever media is dirty, fibrous or abrasive. Typical areas of use include:

• Chemical and biochemical plants – for aggressive or solids-laden process streams

• Pulp and paper mills – stock, fibre, pulp and white water lines

• Chemical fibre production – fibres, slurries and additives

• Pharmaceutical plants – viscous or solid-containing intermediates and effluents

• Environmental and wastewater applications – sludge, screenings, recycled streams and industrial effluent

In these duties, the valve provides both reliable isolation and manageable maintenance, which is critical for plants chasing higher availability and lower operating costs.

Technical Data at a Glance

To match the DQ-Series Knife Gate Valve to your plant, it helps to know the available envelope:

• Nominal Size (DN): DN50 to DN1200

• Pressure Rating (PN): PN10 to PN16 / ANSI 150LB

• Connection Type: Wafer

• Operating Temperature Range: -29°C to +100°C

• Seat Types: Metal seat or soft seat options

• Tightness Standard: MSS-SP81

• Body Materials:

  • WCB

  • CF8

  • CF8M

  • CF3M

These combinations allow you to adapt the valve to corrosive, abrasive or mildly aggressive media, based on your process conditions.

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Smart Construction Details That Make a Difference

Beyond the basics, several design elements in the DQ-Series help operators and maintenance teams in real-world use:

Double Stem Bearing

• Two bearings at the top of the yoke support the stem

• This reduces operating torque, making the valve smoother and easier to operate – manually or via actuator

Internal Packing Arrangement

• The packing gland and packing are located inside the body design

• This helps limit leakage to atmosphere and improves the overall sealing integrity of the valve

Travel Aligning Block

• A travel aligning pack with a soft backing material and stainless steel screw is positioned at the inlet

• It supports the gate and ensures accurate alignment during closing

• That means improved tightness and less risk of jamming when solids are present

Replaceable, O-Ring Backed Seats

• Seats are backed by an O-ring, allowing self-compensation as wear occurs

• This maintains tight shut-off over a longer period

• Seat replacement is quick, with options such as:

  • Metal seated

  • EPDM seated

  • PTFE seated

Precision Gate Design

• The gates are precision-ground and hard chrome plated

• This improves abrasion and corrosion resistance, especially in slurry and fibre-rich duties

• The arc-shaped lower edge adds extra cutting power, making it particularly effective in pulp and slurry applications

Flexible Port Geometry

• Depending on your control requirements, the port can be configured as:

  • V-port

  • Triangle port

  • Hexagon port

• This allows finer flow control and more stable regulation in challenging duty conditions

If you are unsure which port style or material combination you need, KV Controls can help evaluate your process and recommend a suitable configuration.

FAQ – DQ-Series Knife Gate Valves

Q1: What is the main difference between a DQ-Series Knife Gate Valve and a standard knife gate valve?
A: The DQ-Series Knife Gate Valve is specifically engineered for slurry, fibre and solids-handling applications. Its compact one-piece body, arc-shaped gate and self-cleaning, shearing action make it more effective in preventing clogging and maintaining tight shut-off than many standard knife gate designs.

Q2: Which seat materials are available for the DQ-Series and how do I choose the right one?
A: The DQ-Series offers metal, EPDM and PTFE seat options. Metal seats are suited to high-temperature and highly abrasive services, EPDM works well with many water and wastewater duties, and PTFE is ideal where chemical resistance and clean shut-off are required. KV Controls can help you select the best seat material based on your temperature, pressure and media.

Q3: Can KV Controls assist with specifying actuators and integrating the DQ-Series into my control system?
A: Yes. KV Controls supports customers with actuator sizing, torque calculations and selection of pneumatic or electric actuators. We also assist with defining fail positions and integrating the valve into your PLC or SCADA-based control system, ensuring reliable, automated operation.

Why Work with KV Controls for DQ-Series Knife Gate Valves?

Choosing the right valve is about more than just picking a catalogue code. At KV Controls, we support you with:

• Application-based valve selection – we look at your pressure, temperature, media and solids loading

• Material and seat recommendations – to balance cost, durability and chemical compatibility

• Actuator and control advice – manual vs pneumatic vs electric, including required torque and safety positions

• Lifecycle support – from initial specification through commissioning and beyond

Our goal is to ensure every DQ-Series Knife Gate Valve we supply is correctly sized, correctly configured and properly integrated into your process.

Ready to Improve Slurry and Fibre Handling in Your Plant?

If your operation struggles with plugging, high maintenance or unreliable shut-off in lines carrying slurries, fibres or solids, it may be time to review your valve selection.

The DQ-Series Knife Gate Valve from KV Controls is designed for exactly these conditions – combining compact construction, strong cutting action and easy seat replacement to keep your process running smoothly.

For quotations, technical advice or assistance with valve selection, contact:

📧 sales@kvcontrols.co.za

KV Controls is proud to support South African industry with robust, application-ready knife gate valve solutions that bring control and efficiency together in one reliable package.