50mm Hansen Check Valve BSPT

The spring in the valves is made of 302 grade stainless steel, and may eventually corrode in the salt water. The spring is available as a replacement part if required. All other parts of the valve are fully resistant to salt water.

Work out the flow of your pump (your pump installer/supplier can help you here) then refer to Choosing the correct Foot or Check Valve under the Technical Info / Pressure & Flow Rates Tab of each product. 

Yes, the Hansen Check Valve can be serviced inline and any parts replaced if required.

No, although pumping sand is unadvisable because of the damage to your pump. You will find with the screw cap service access to the Hansen Foot Valve you only need to replace the parts that wear in these circumstances. Another suggestion would be because the Hansen Foot Valve can be installed at any angle you may be able to install the Hansen foot valve vertically above your suction pipe and keep it above the sand.

No not necessarily, again because of the higher flow efficiencies of the Hansen Foot Valve you match your flow with the head loss your pump can afford, generally you will find the Hansen Foot Valve size will be less than the pipe diameter. To choose the correct sized valve for your application, refer to the Choosing the Correct Foot or Check Valve Page under the Technical Info / Pressure & Flow Rates Tab of each product.