Important points regarding the piping of built-in tank chillers and surrounding piping
A chiller is a device that regulates the temperature of raw materials and machinery, and consists of refrigeration circuit, a water tank, and piping that connects the two.
Piping carries cooling water to equipment, and if clogged operation or air pockets occur, it can affect factory productivity.
This time, we will introduce key points such as the piping of tank-mounted chillers, surrounding piping, and bypass circuit installation.
1. Important points regarding piping for built-in tank chillers
In the case of chillers with built-in tanks, the pump is attached to the discharge side of the tank, so the discharge force is sufficient, but the inlet side is simply connected to the tank and no power is applied.
In order to ensure that the same amount of circulating water as the pump discharge always flows into the tank, the load side must be a closed system. It is generally not possible to connect directly to an open liquid tank.
If you are cooling an open tank, you should install a heat exchanger or pump between the tank and the tank to cool it indirectly.You can also use an immersion type heat exchanger that is immersed in the tank.
2. Install an air vent valve in the piping around the chiller.
One problem to be careful of in the piping around the chiller is air entrapment.
Air pockets can cause water hammer and erosion, so they can be prevented by using air bleed valves.
What is an air bleed valve?
An air vent valve is a component that efficiently removes air from piping, and consists of a valve body and a float.
When the pipe is full of liquid, the float rises and comes into close contact with the valve disc, sealing the inside of the pipe. However, when the amount of liquid in the pipe decreases, the float drops, and the air inside escapes through the gap with the valve disc.
Air bleed valve installation location
Air bleed valves are not necessarily installed anywhere. They are primarily used on the discharge side of pump piping, but they are most effective when installed in areas where air is likely to accumulate, such as the following:
(1) The top of the pipe
Gas has a lower density than liquid, so it tends to collect at the top of the pipe. Installing an air vent valve at the top of the pipe can efficiently remove air.
(2) Long horizontal piping
Normally, when installing horizontal piping of a certain length or longer, it is desirable to create a slope so that the air inside the piping is concentrated in one direction, but if it is difficult to create a slope due to the equipment, or if the horizontal piping is too long, an air vent valve is installed midway along the piping.
(3) Torii Piping
Torii piping is piping that is installed over an object like a torii gate to avoid obstacles. Air tends to accumulate at the top, making it difficult to release in either direction, so the installation of an air vent valve is essential.
3. Bypass circuit to prevent chiller blockage
It is also important to prevent blocked operation in chiller piping. Finally, we will explain the necessity of bypass circuits to prevent blocked operation and key points to consider when installing them.
The need for bypass circuits
If the discharge piping of a chiller or other refrigeration equipment becomes blocked, the liquid trapped inside the pump casing may overheat, damaging rubber or plastic parts and sealing materials, or shortening the life of the pump itself.
Furthermore, if circulating water remains in the heat exchanger, the water may freeze and expand, potentially damaging the heat exchanger.
To reduce such risks, it is important to install a bypass circuit.
Four points to note when installing a bypass circuit
When installing a bypass circuit in chiller piping, keep the following four points in mind.
The first point is to install a globe valve that can adjust the flow rate as the gate valve of the bypass circuit. If you select a ball valve, you will not be able to control the flow rate, so be careful.
The second key point is to use flexible hoses whose lengths can be adjusted. Chiller units often have fixed positions for circulating water supply and return pipes, making it difficult to adjust the length of the bypass section, so using flexible hoses makes piping installation easier.
The third point is to use union or flange arrangements for fittings. Socket welding and butt welding are not very suitable when considering the connection and disconnection of piping.
The fourth point is to use one-touch couplings when setup changes and maintenance are required frequently. For example, depending on the product type, parts that make up part of the piping route, such as rolls and molds, may need to be replaced frequently.
In addition, one-touch fittings come in two types: "open type," in which the internal fluid flows out when the fitting is removed, and "open/close type," in which the valve closes with a spring, preventing the contents from flowing out. It is important to use them according to how you will use them.
4．まとめ
Chillers, which efficiently cool equipment and raw materials, are essential for stable factory operation. Therefore, constant attention must be paid to problems such as blocked operation and air pockets.
Installing air vent valves and using piping that prevents blocked operation will prevent problems and ensure productivity is not reduced.
