German ASKI valves ASKI models ASKI prices

ASKI valves are globe valves that use a diaphragm as the closing element to seal the flow passage, shut off fluid, and separate the valve body cavity from the valve bonnet cavity. Diaphragms are commonly made of elastic, corrosion-resistant, non-permeable materials such as rubber and plastic. Valve bodies are mostly made of plastic, fiberglass, ceramic, or metal with rubber lining. They feature a simple structure, good sealing and anti-corrosion performance, and low fluid resistance. They are used for media with low pressure, low temperature, strong corrosiveness, and suspended solids. Structural forms include weir type, straight-through type, and gate plate type. Drive methods include manual, pneumatic, and electric.

ASKI valve functions

A diaphragm valve contains a flexible or composite diaphragm inside the valve body and bonnet, with a closing member connected to the diaphragm via a compression mechanism. The seat can be weir-shaped or the wall of a straight-through flow passage. The advantage of a diaphragm valve is that the operating mechanism is isolated from the media path, ensuring the purity of the working medium and preventing media impact on the operating components. Additionally, no separate sealing is required at the stem unless used as a safety facility for controlling hazardous media. In diaphragm valves, only the diaphragm and valve body contact the working medium; both can be made from various materials, allowing ideal control of multiple working media, especially those with chemical corrosiveness or suspended particles. The operating temperature is usually limited by the materials of the diaphragm and valve body lining, with a range of approximately -50 to 175°C. The diaphragm valve has a simple structure, consisting mainly of three components: the valve body, diaphragm, and valve head assembly. It is easy to disassemble and maintain quickly, and diaphragm replacement can be completed on-site in a short time.

ASKI valve working principle

Diaphragm valves replace the valve core assembly with a corrosion-resistant lined valve body and a corrosion-resistant diaphragm, using diaphragm movement for regulation. Valve body materials include cast iron, cast steel, or cast stainless steel, lined with various corrosion-resistant or wear-resistant materials; diaphragm materials include rubber and PTFE. The lined diaphragm offers strong corrosion resistance, suitable for regulating highly corrosive media such as strong acids and alkalis. Diaphragm valves have a simple structure, low fluid resistance, and higher flow capacity than other valve types of the same specification; they are leak-free and suitable for regulating high-viscosity media and media with suspended particles. The diaphragm isolates the medium from the upper chamber of the valve stem, so there is no packing and no external leakage. However, due to limitations of diaphragm and lining materials, pressure and temperature resistance are relatively poor, generally applicable only up to 1.6MPa nominal pressure and below 150°C. The flow characteristic of a diaphragm valve approximates quick-opening; it is nearly linear before 60% travel, and flow change is minimal after 60%. Pneumatic diaphragm valves can be equipped with feedback signals, limiters, and positioners to meet needs for automatic control, program control, or flow regulation. Feedback signals for pneumatic diaphragm valves use non-contact sensing technology. This product uses a diaphragm-type actuating cylinder instead of a piston cylinder, eliminating the drawback of piston ring damage causing leakage and failure to open/close the valve. In case of air source failure, the handwheel can still be operated to open or close the valve.

ASKI valve applications

A diaphragm valve is a special type of shut-off valve whose closing element is a diaphragm made of soft material, separating the valve body cavity from the valve bonnet cavity. Due to limitations in valve body lining and diaphragm manufacturing processes, producing large linings and large diaphragms is difficult; therefore, diaphragm valves are not suitable for large pipe diameters and are generally applied in pipelines ≤ DN200. Due to limitations of diaphragm materials, diaphragm valves are suitable for low-pressure and low-temperature occasions. Generally, temperatures should not exceed 180°C. Due to their good anti-corrosion performance, diaphragm valves are mostly used in devices and pipelines for corrosive media. The applicable temperature and media for diaphragm valves are limited by the valve body lining material and diaphragm material.

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