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Do You Know What to Pay Attention to When Purchasing Butterfly Valve?

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Matters Needing Attention in Design and Selection of Butterfly Valve

 

For civil HVAC system, the following points should be noted in the design and selection of indicating butterfly valves:

 

Balance Between Handle Butterfly Valve and Turbine Butterfly Valve

 

According to the engineering experience, the handle modulating butterfly valve is recommended when the pipe diameter is less than or equal to DN 100 mm and the worm gear seal butterfly valve is recommended when the pipe diameter is greater than or equal to DN 100 mm. The large pipe diameter of handle butterfly valve will not move the handle when switching due to corrosion and insufficient operation space. Because the handle butterfly valve is cheaper than the turbine butterfly valve, so you should consider comprehensively in the selection.

 

 

Balance Between Flange Butterfly Valve and Wafer Butterfly Valve

 

According to the engineering experience, on the premise of ensuring the installation quality, the clamp single offset butterfly valve is suitable for the pipe diameter less than or equal to DN300 and the pressure less than 1.6Mpa because the price is relatively cheaper, while the flange butterfly valve is suitable for the pipe diameter greater than DN300. Of course, for the pipe larger than DN300 and pressure less than 1.6Mpa, the double clip butterfly valve can also be used, but you need to fully consider the installation level and system pressure to prevent leakage.

 

Balance Between Hard Seal Butterfly Valve and Soft Seal Butterfly Valve

 

Both sides of the seal can be made of metal or other hard materials, which are called "hard seal". The sealing performance of hard seal is poor and it is difficult to achieve "zero leakage", but it has high temperature resistance, wear resistance, good mechanical performance, and high price. When one side of the seal is made of metal material and the other side is made of elastic non-metal material, it can be called "soft seal". It has good sealing performance and low price, but it is not resistant to high temperature, easy to wear, and poor mechanical property. Soft seal is recommended for HVAC system because of its low price, while hard seal is generally used in chemical, high temperature, and high pressure special conditions.

 

 

Precautions of Butterfly Valve in Purchasing Process

 

According to the standard GB / T12238-2008 "Flange and Pair Clamp Connection Elastic Sealing Butterfly Valve" and engineering experience, the following points should be paid attention to when purchasing triple offset butterfly valve in civil HVAC system:

 

•The material of each part of the globe butterfly valve should be clear when inquiry, so as to avoid the price difference caused by different materials, thus affecting the fairness of procurement. The main components of intake butterfly valve are valve body, valve sealing ring (seat), valve plate, valve stem, valve stem bearing, and valve stem seal.

 

•The pipe with nominal pressure less than or equal to PN10 can be made of gray cast iron HT200, while the pipe with nominal pressure greater than PN10 should be made of ductile iron, carbon steel casting, or stainless-steel casting.

•The sealing ring of valve body is usually made of EPDM or NBR, which has good oil resistance.

 

•The common material of valve stem is 45 steel chrome plating or stainless steel (2Cr13).

 

•The valve plate is usually made of nodular cast iron chrome plated or stainless steel (304) because the air conditioning water system will rust after long-term operation, which will accumulate at the valve plate, thus affecting the switch and sealing.

 

The price of motor operated butterfly valves made of different materials varies greatly, so you should determine the material according to the pressure of the system, the level of operation management, and the importance of the electrically operated butterfly valve when purchasing. The unified standard should be targeted, which can facilitate price comparison and negotiation.

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