Check valves are used as one-way or non-return valves in practically all industrial applications. Check valves are easy instruments that serve a crucial duty by preventing reversal flows, preventing harm, and guaranteeing effective operations. Different check valve designs are created for particular applications. Here are some of the most popular varieties of check valves and some of their suggested uses to assist you in selecting the best one for your needs.
What is a check valve?
A check valve is a mechanical component that only permits one direction of fluid flow. The valve blocks the path for fluid to flow as the direction of flow changes. They are also referred to as one-way valves or non-return valves. It is typically used in fluid pipelines to stop fluid backflow.
The check valves typically have two ports, one for the entrance and one for the outlet. Figure 1 depicts a standard check valve. An engineer by the name of Frank P. Cotter created the first check valve in history in 1907. Following this, Nikola Tesla created a revolutionary check valve with no moving parts, as seen in figure 2. The Tesla valve is another name for this valve.
Function of the Check Valve
The pressure differential between the outlet and intake ports is a major factor in the check valve’s operation. The valve opens the route for fluid to flow when the pressure on the inlet side is high. When the flow is reversed and the pressure at the outlet port exceeds the pressure at the intake port, the valve closes and the flow is stopped. These valves can be operated without the use of an actuation mechanism, a person, etc.
The majority of the time, check valves are positioned in areas of an operation where fluid backflow could harm the system and render it useless. In the case of reverse osmosis, the fluid needs to transit the system only in one direction; thus, to achieve this, the check valve is inserted in the flow line. Similarly, the pipelines of sewage systems feature check valves to ensure that waste can only exit the system and not re-enter it.
Installation of the Check Valve
Three things are necessary to understand the valve selection and installation: valve orientation, sealing pressure, and cracking pressure. The cracking pressure is the lowest pressure at the inlet port needed to even minimally open the route. The resealing pressure is the lowest pressure at the valve’s outlet port that completely closes the valve to stop fluid from flowing backward. The valve should be installed in accordance with the flow direction, which is why it is advised to double-check the valve’s operational direction before installation.
Materials of Check Valve
Using these materials to manufacture this check valve
The majority of check valves are constructed of sturdy materials to handle high-pressure situations. Check valves are frequently made of the following materials:
Polyvinyl chloride (PVC) is flexible and resistant to corrosion. PVC’s smooth surface makes it easy for the pieces of the check valve to move around.
Chlorinated Polyvinyl Chloride (CPVC): PVC and CPVC are similar in quality; however, CPVC can withstand applications that require high temperatures.
Bronze: Bronze is corrosion-resistant, can be cast in intricate configurations, and can be used for low- and medium-pressure applications.
Brass: Brass is less expensive than bronze and shares the same properties, including machinability.
Cast Iron: Due to their superior corrosion resistance, cast iron check valves are utilized for hot and cold water, HVAC, steam, gas, and utility services.
Ductile Iron: Due to its higher than 3% carbon content, ductile iron is easily bent and molded. It is more easily formed into check valves and stronger than cast iron.
Iron: Applications involving steam, water, oil, and gas use iron. It can withstand a variety of pressures and temperatures. Its superior performance more than offsets its hefty price.
Stainless Steel: Stainless steel is rust-proof, strong, and suitable for use in demanding environments, including chemical applications.
Polypropylene (PP): Check valves are made of polypropylene (PP), which has a remarkable corrosion resistance that surpasses that of CPVC and PVC.
PVDF (Polyvinylidene Difluoride) is a material that is used in applications that require a high degree of purity and resistance to acids, solvents, and hydrocarbons.
Cast Steel: Due to its resilience to sudden impact without deforming, breaking, or bending, cast steel is used to make check valves. Additionally, it is simple to form into any style of check valve.
The following variables affect the choice of valve type and material:
- The material’s suitable for the fluid in action.
- dimensions of the pipeline and the available space.
- requirement for sealing and cracking pressure.
- Either a horizontal or vertical installation is possible.
- the size and contours of the envelope.
- accessibility for maintenance, repair, and inspection.
- operating conditions and the temperature of the fluid in motion.
Application of the check valve
Check valves have been used in a wide range of applications. As an example, they are frequently installed on a pump’s outlet side to prevent backflow. Check valves are crucial for maintaining water pressure in the pipes since centrifugal pumps, the most prevalent kind of water pumps, are not self-priming. Additionally, HVAC (heating, ventilation, and air conditioning) systems frequently employ check valves. A coolant is pushed up many stories in huge buildings using HVAC systems, for instance. These check valves are set up to prevent coolant from flushing back down.
Check valves are most frequently employed in:
- Power Industries
- Food and Beverage Companies
- Oil and Gas Plants
- Pharmaceutical Industries
- Steam heat recovery
- service at high temperatures
- thermal service
- High-pressure safety service
- System safety for utilities
- Cut off the cooling.
- production and refinement of petroleum
- processing of hydrocarbons
The following applications are possible, depending on how well the check valves function:
- To stop the system from being harmed by fluid backflow.
- To guarantee the avoidance of contamination brought on by fluid backflow.
- To prevent a pipeline from being siphoned.
- To keep the vacuum seal in place.
steam heat recovery. Using check valves, you can regulate the flow of gases or liquids. Check valves are economical tools that stop waste and safeguard machinery. The graphic below shows how check valves fluctuate based on flow rate, media gravity and temperature, line size, pressure, and flow velocity. The body, seat, disc, and cover are the four separate components of a standard check valve. Check valves come in many variations to suit a wide range of applications. Mcneil Instruments Inc. is one of the most popular check valve manufacturers, stockists, suppliers, and exporters in India and worldwide.