Knife gate valves help you control the flow of slurry, even when the material is abrasive or contains solids. If you choose the right valve, you reduce blockages, leaks and downtime.
Kramp stocks Metaltecnica Zanolo (MZ) knife gate valves for agricultural slurry systems, including MZ cast-iron knife gate valves and MZ cast-iron knife gate bidirectional valves. After reading this article, if you are not sure which one fits your setup, speak to a Kramp product specialist.
When are knife gate valves used in agriculture?
A knife gate valve is a full-flow valve. A blade moves vertically to open the line or shut it off.
In slurry handling, this design works well because:
- The stainless steel blade resists corrosion and can cut through dense or partially settled slurry.
- The valve can seal reliably when the slurry contains solids.
- The compact body suits tight installations on tankers and pump sets.
You usually see these valves on:
- Slurry tankers and umbilical systems.
- Farm digesters and biogas plants.
- Slurry storage tanks, reception pits and transfer lines.
Which knife gate valve should you choose?
Kramp stocks several Metaltecnica Zanolo options, but two common choices for slurry systems are the MZ cast-iron knife gate valves and the MZ cast-iron knife gate bidirectional valves. They share the same basic purpose, but they differ in sealing, flow direction and how likely they are to clog.
Shop MZ cast-iron knife gate valves
Shop MZ cast-iron knife gate bidirectional valves
Main differences between the two MZ valve types
MZ cast-iron knife gate valves
MZ cast-iron knife gate valves are unidirectional knife gate valves without discharge. They have a cast iron body and a vertically moving stainless steel blade.
You can operate them manually with a hand wheel or lever, or fit an actuator such as hydraulic or pneumatic. The EPDM rubber seal sits in a screwed-on sleeve.
(EPDM is a type of synthetic rubber commonly used in slurry applications because it stays flexible and resists ageing in wet, outdoor conditions.)
When slurry pressure comes from the correct direction, it pushes the blade against the seal and helps the valve close tightly. Because the body has internal spaces to house the blade, you should plan for regular cleaning, especially if you handle thick slurry with a lot of fibre.
This type is often chosen when cost matters and the flow direction is fixed.
MZ cast-iron knife gate bidirectional valves
MZ cast-iron knife gate bidirectional valves are bidirectional knife gate valves. The cast iron body is made of two halves joined with bolts. The stainless steel blade is thicker, which improves stability under load.
Its EPDM seal has an internal steel core. The valve seals through full contact between the blade and the perimeter of the seal. With no internal cavities, it is less likely to clog when slurry contains solids. Internal guide rings help keep the blade stable at medium pressures.
This type suits systems where flow direction may change or where clogging risk is higher.
The questions to ask before you decide
Do you need bidirectional sealing?
If your system can run in both directions or you might reverse flow during operation, choose MZ cast-iron knife gate bidirectional valves. MZ cast-iron knife gate valves are designed for one flow direction.
Is clogging likely?
If you handle slurry with high solids, bedding fibres or settled material, MZ cast-iron knife gate bidirectional valves are usually the safer choice because they have no internal cavities. MZ cast-iron knife gate valves can work well, but they may need more frequent cleaning.
What maintenance can you manage?
If access is limited, you may prefer the design that is less prone to build-up. If you can inspect and clean the valve regularly, you may have more flexibility.
Do you need extra blade stability at medium pressures?
If your installation puts more mechanical load on the blade, MZ cast-iron knife gate bidirectional valves include internal guides that help reduce unwanted bending.
If you want help matching a Metaltecnica Zanolo valve to specific tankers, pump sets or digester lines, contact us. A product specialist can check sizing, actuator options and installation details.
This article is based on content originally published by Metaltecnica Zanolo. The original version can be found here. Content used with permission.
