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Aylesbury 'KB' Type



Available here at Keraflo, Aylesbury ‘KB’ type float valves are operated by a transfer of weight in an actuator tube which causes the valve to open or close. The arrangement of the float and buoy assembly produces a delayed change of balance in the actuator as the water level alters. The total assembly is relatively light with no pressure related stresses. As a result, the valve does not require any supporting structure.

Aylesbury ‘KB’ type float valves have a variable delayed action and feature a chain in place of a rigid float arm, enabling virtually unlimited opening and closing levels. This allows for a considerable drop from the valve to the water level, overcoming issues associated with drop arms.

The versatility of the Aylesbury ‘KB’ type float valves also make them suitable for installation either directly into a tank or into a raised valve chamber, particularly where air gaps are required. Changes in water levels and differentials can be made quickly by the installer or maintenance engineer without tools.

This feature is particularly useful where water demand changes either due to seasonal factors, building occupancy or where the commissioning of a facility is phased, as it reduces the risks associated with excess water being stored for too long.

Below you will find sales literature for our Keraflo Aylesbury valves together with our Keraflo Product Guide and Keraflo Specification Guide - all available for download.


Read the technical information regarding Aylesbury ‘KB’ type float valves for more details about these units, or contact us to discuss the technology with our knowledgeable members of staff.

Selected Aylesbury ‘KB’ type float valves to fit to your cold water storage tanks? Be sure to shop our range of spares for Aylesbury ‘KB’ type float valves to keep them functioning perfectly for longer.

Please click here to find out more about our electronic Tanktronic tank management system that monitors water levels, temperature and manages & controls tank filling. 

The Tanktronic tank management system now has a new product range addition: the Keraflo Tanktronic Servo Ceramic Valve (SCV) which is a compact precision-engineered valve, for unique motorised filling of cold water storage tanks that brings greater control to the system.


Technical Information
Sizes for 'KB' Type Delayed Action Float Valve

This unique valve is ideal for use with pumped systems, water treatment plants and many other applications including:

  • Industrial tanks 
  • Pumped systems 
  • Underground tanks 
  • Rain (grey) water tanks and reservoirs
  • Industrial feed and expansion tanks
  • Process tanks


The flexibility of ‘KB’ valves can assist with improving water quality where buildings are partially commissioned or occupancy varies, at different times of the year.

Air Gaps for Industrial Tanks

The ‘KB’ Type is ideal for fitting into a tank without a lid or raised valve chamber and where the vertical drop from the valve to the water level may be considerable.

Pumped Systems

The adjustable and potentially large difference between opening and closing levels can allow a large volume of water to be admitted to the tank each filling cycle. Pumps and pump sets are often controlled to run for a minimum of 3 minutes. If the water demand is satisfied before this time and an auxiliary hydraulic accumulator is not fitted, the pumps will run against a closed valve at zero efficiency.

The fill volume can be set to equal or exceed this volume to ensure the pump/s run for at least 3 minutes. Where a pump set is used solely for transferring water from a break tank to an elevated storage tank the ‘KB’ Valve can dispense with the need for an auxiliary hydraulic accumulator.

Pump efficiency and initial sizing can be further enhanced using a float valve with little internal resistance. Consequently the High Flow version is often better suited to these applications than the Standard Flow version which is ideal for mains water pressure applications.

Case Studies

Keraflo valves reduce risk of cold water stagnation at Queens Hospital Burton on Trent



In a recent refurbishment project, Keraflo Ltd. has supplied four KP Type float valves to control the water levels in eight Dewey Waters cold water storage tanks installed at Queens Hospital, Burton on Trent. These 1,500 litre tanks are installed in pairs in four tank rooms, replacing the original eight single tanks which had reached the end of their operational lives and had, due to their size, caused access problems. Each pair of tanks is installed in a separate block and supplies all hot down feed and domestic cold water services. Keraflo valves were selected by the design consultant in order to ensure simultaneous fill of dual on-line tanks.

Opened by Her Majesty The Queen in 1995, Queen’s Hospital, was a major capital development which saw the centralization of Burton-on-Trent’s hospital services to newly constructed premises on the site of the former district hospital in Belvedere Road, two miles from the town centre. This subsequent refurbishment of 30 year old buildings that were part of the original district hospital includes the installation of four new Dewey Waters tanks (two cold water down services and two DHWS cold feed tanks) in each tank room.

These were located in four separate blocks housing the Burton Clinic/Wards 19 & 20, ‘F’ Block, Accident &Emergency and the Geoffrey Hodges Ward. The consulting engineers Roger S Bullock Associates commented: ‘Each pair of cold water services tanks was connected for parallel operation and to achieve simultaneous flow, a Keraflo Aylesbury KB Type 2’’ (50mm) pilot valve was installed in each tank, controlling a Keraflo KP Type float valve with upstream pressure sustaining valves installed. The system is working very well with equal water flow being developed to each tank, thereby avoiding water stagnation.’

Aylesbury KB Type valves are operated by transfer of weight in an actuator tube which causes the valve to open or close in a single delayed action, rather than giving the gradual opening and closing achieved with a conventional ball valve. Attached to the actuator is a 2m long chain with a float and buoy assembly which offers a fully variable differential between opening and closing water level settings by simple adjustment of the length of chain between the actuator and the floats. Changes in water levels and settings can be made quickly by the installer or maintenance engineer, as no tools are required, making it particularly suitable for applications in buildings with seasonal occupancy. Water discharge is via an ‘up and over’ pipe to facilitate air gap compliance.

Keraflo delayed action float valves avoid water hammer, valve bounce and pump hunting, which leads to improved pump performance and maximum energy efficiency. In addition, they reduce the risk of stagnation and water borne diseases which can occur when stored water is not used for long periods of time, particularly at high ambient temperatures in the summer months.

The Keraflo valves were supplied to Dewey Waters Ltd. via Keraflo Agents Hurlstone & Partners and installed by Daly Engineering Services Ltd.

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Aylesbury 'KB' Type
Fully Variable Delayed Action Float Valve suitable for tanks with or without raised valve chambers
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