The knife gate valve to manage your liquids

What is a knife gate valve and what are its advantages over traditional gate valves?

The guillotine valve is a piece of equipment designed for the isolation of networks in which the rate of solid matter in suspension is high. This valve is suitable for fluids of a gritty, corrosive, abrasive nature, slimy or muddy. The knife gate valve is composed of three parts which are the interception blade, the body and the opening device. The knife gate valve is generally used for the purpose of making changes to the flow rate of a fluid. It is also used to regulate the pressure level and to guarantee the protection of the machines. When the valve is fully open, it reduces pressure drops.

Knife gate valves are designed for harsh environments. They are particularly useful in the field of sanitation, because they can thus be equipped with a stainless steel shovel that is resistant to acids. Thus, the knife gate valve is perfectly resistant to corrosion. The knife gate valve must be in the open or closed position. Therefore, it should not be used to regulate the flow of a liquid, unless it is equipped with a reinforced scoop.

Unlike traditional models, the knife gate valve has many advantages. The first is its U-shape which provides excellent sealing. Thanks to its design which is quite unique, the knife gate valve is easy to install, disassemble and maintain. In addition, the presence of a knife shovel provides an excellent breaking effect, since it can break all kinds of debris. Finally, the knife gate valve has a very short structure, very light weight and reduced dimensions that allow it to occupy little space.

How to install a knife gate valve in your industry?

The installation of a knife gate valve must be carried out by a professional competent. Before getting started, he must perform certain specific tasks. To start, he must weld the pipes. If this is not possible, it must protect the valve against excessive heat generation. Before installing the valve, all solder waste must be removed. It is also strongly recommended to use dowels to ensure that the fixing flanges are perfectly maintained.

To ensure proper operation of the knife gate valve, avoid installing a 14-24 in. valve in a horizontal pipeline, as the packing will suffer excessive wear in this position. Likewise, it is important not to overtighten the machine screws when they are placed in abutment. Otherwise, you can damage the valve, which will prevent it from working properly.

Regarding the installation of the guillotine valve, it is important to find the necessary torque in order to properly tighten the fasteners. For this, it is necessary to take into account the type of seal, the pressure in the pipe, the material of the screw as well as the lubrication. When installing a valve with an actuator in the horizontal position, you may need support for the actuator. You will then need to screw the valve onto the corresponding flange, taking care to lubricate the fasteners which are stainless steel.

Be sure to tighten the clamp screws alternately. When the valve is installed, it must be prepared for a hydraulic test. If you find a leak, just adjust the trim.

The different types of knife gate valves available on the market

Before talking about the different types of knife gate valves, it is important to know that this equipment is made of different materials. There are stainless steel valves and cast iron valves. Stainless steel valves are very strong and can withstand high pressures. They are perfect for industries like mining. It is also possible to use them for the treatment of waste water, sugar, chemicals or that of paper pulp. The cast iron valve is ideal for low corrosive environments. However, it requires regular maintenance so as not to rust.

Going back to the types of knife gate valves, note that there are several. One-way valve is a model that is waterproof on one side only. It is suitable for water treatment, for paper pulp sludge, but also for sticky sludge created by sugar factories. These valves are ideal for aggressive high temperature environments. The one-way valve has few pressure drops and retention zones. However, it leaks when there is an accumulation of debris.

The two-way knife gate valve meanwhile, ensures a complete seal and prevents the accumulation of solids that could prevent it from closing. It is a one-piece valve that is tight in both directions. It is more expensive than the one-way valve, but is suitable for many uses. The two-way valve is commonly used for lightly charged liquids such as those found in water supply networks.

How do you properly maintain your knife gate valve for optimal performance?

Maintenance of a knife gate valve must be carried out by qualified personnel. When the liquid in the pipes is dangerous, it is important to take extra precautions. To do this, use an appropriate safety device. When servicing a knife gate valve, remember to wear protective clothing and equipment for eyes, face, hands, skin and lungs.

Before working on the valve, take care to disconnect all energy sources, whether electrical, hydraulic or pneumatic. If you were working on the valve due to a packing leak, locate the location of the leak and tighten the nearest injectable packing screw. Proceed to tighten the screw until the leak stops. If, despite your intervention, the leak does not stop, depressurize the pipe and unscrew it in order to inject small quantities of packing. Then install the packing screw and tighten again.

If your intervention aims to replace the main seal, start by dismantling the valve in order to access the main seal. Since you will have access to the guillotine, remember to lift it to clean it. The guillotine must not have any digging or scratches. To do this, polish it with a scotch-brite pad to eliminate any irregularities.

Before replacing the main seal, it is important to clean the inside of the body, but also to check it in order to detect any damage. Once all these checks are done, replace the main seal and insert the guillotine scrapers. Two scrapers are required per half-body. Next, bring the two half-bodies together and apply silicone lubricant to the edges. Insert the gate from the top, tighten the body screws diagonally and reassemble the valve.

Tips and Tricks for Using Your Knife Gate Valve to Handle Liquids Effectively

Improper use of the knife gate valve can cause damage. For this reason, be sure to select equipment that meets your performance requirements. Be careful not to exceed the pressure ratings or temperature. The assembly, operation and maintenance of the knife gate valve must be entrusted to a professional who has the required qualifications. Failure to comply with safety precautions can result in fatal accidents or property damage.

To use a knife gate valve safely, it is recommended not to leave the valve components unprotected if they could be a source of danger. Be careful not to use the valve without the contact protection and not to permanently hang accessories on it. Also avoid painting product identification and warning labels. When you want to perform maintenance on a knife gate valve, consider having it decontaminated if it has been exposed to a dangerous product. Be sure to reactivate the safety elements as soon as your maintenance work is completed.

It is strongly advised not to use spare parts that are not approved on a knife gate valve. If you do not use original parts, the civil liability of the manufacturer is automatically canceled. Knife gate valves are only reliable for the purpose for which they are intended. It is important not to exceed the operating limits which are mentioned on the identification label or on the technical sheet of the product.

Be sure to follow all applicable standards and regulations regarding the prevention of accidents when handling the valve. To avoid damage, handle the valve with care. Also be sure to leave the protective cap covers on the valve until it is installed. Finally, it is recommended not to lift the valve by the handwheel, but to use a lifting system of rated capacity suitable for the weight of the valve.