​Unit 315 session 4a Methods of filling large-scale cisterns

​In domestic cistern installations up to 1000 litres, this is

usually a float operated valve to BS 1212.

In large-scale cisterns, however, other means of filling the cistern are available:

● float operated valves

● solenoid valves.

​Follow the link and answer the questions on the next slides.

​https://knowledge.bsigroup.com/search?type=products&query=float+operated+valves

​There are basically four types of float operated valve (FOV) that can be installed on large-scale cisterns.

These are:

● BS 1212 Parts 1 and 2 float operated valves

● equilibrium float operated valves

● pressure operated float valves

● Keraflo delayed action float valves.

​BS 1212 Parts 1 and 2

These are the most common types of FOV.

The main problem with this type of FOV is that they are very restrictive to water flow and incur a much greater pressure (head) loss than other types of FOVs, making cistern filling a long process.

Wear on the washer and orifice can also be problematic when the valve is in constant use.

They are, however, satisfactory when intermittent use is anticipated.

​Equilibrium float operated valves

The equilibrium FOV offers a greater flow rate and lower pressure loss than the BS 1212 type and are especially beneficial for large cisterns with a high-pressure inlet cold water supply

​Pressure operated valves

The pressure operated FOV uses the pressure of the cold water main to assist the valve closure by the use of a pilot valve controlled by the lever and the float.

​Keraflo delayed action float valve

An alternative approach to cistern filling is the Keraflo delayed action float valve. This type of valve only opens when the water falls to a pre-set level in the cistern, opening fully to achieve a fast cistern fill. The benefits here are that not only does the cistern fill quickly but also that the velocity of the water entering the cistern means that the water will mix with the cistern contents

preventing stagnation.

​Solenoid valves

A solenoid valve is an electromechanical valve that controls the flow of water into the cistern. The solenoid is an electromagnet that operates when an electrical current runs through the coil.