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CT Holledge

Pneumatic and electronic level and pressure measurement systems.



• Suitable for hygienic applications

• High accuracy

• Long term proven reliability

• Rugged construction

• Simple installation and set-up

• Standard and bespoke units

• Pneumatic systems for hazardous areas

• Liquid and slurry continuous level measurement

• Continuous pressure monitoring


Level Control


Industry's requirements for level and pressure measurement are as varied as industry itself. Finding a system which can cope with that wide scope and do it accurately, safely and with absolute repeatability is one of the key tasks facing today's process manager. With hazardous products and harsh environments to handle, perhaps requiring intrinsically safe equipment, one of the main factors in choosing a level/pressure system must be its reliability and toughness.


Efficient Level Measurement Solutions


For industry to benefit from the installation of level measurement systems, the selected system must be reliable, repeatable and accurate. In addition, it should be installed quickly, with a minimum of costly down time and it should provide an interface with data acquisition and control equipment.

By employing equipment that satisfies these criteria companies can increase both their efficiency and productivity.


However, with so many different techniques to choose from, selecting the best method for your application is difficult.


We at CT Holledge, with our range of pneumatic and electronic pressure sensors, will assist you through the minefield of system selection and supply you with equipment that not only meets your requirements but exceeds them.


CT Holledge "PB" systems


There are many reasons for the polarity and continued success of the Holledge pneumatic "PB" (pressure balance) system. Firstly it is attractive due to its proven reliability. It is also intrinsically safe, has a low cost of installation and exhibits high accuracy and repeatability.


The sensor - A pressure sensitive diaphragm - can be matched to most requirements. Whether it's a hygienic application such as brewing, dairy or food, or a corrosive one, such as chemicals or CIP (cleaning in place), there is a Holledge sensor to suit. CT Holledge helps you to achieve the highest accuracy of measurement with minimal risk to your production process.


The system can be used to measure pipe pressure, vessel contents or other parameters such as mass or density (SG).


The principle - The "Pressure Balance" principle is simple and comprises a transmitter, an air flow regulator, and a receiving instrument, usually a P to I (pressure to current) converter or a pneumatic gauge.


A constant flow of instrument air - at a pressure above the maximum process pressure - is fed into a transmitter. With no process pressure applied, the air is vented past the transmitter diaphragm to atmosphere. When the process exerts a pressure on the diaphragm, the diaphragm distends slightly, reducing the size of the vent, thus restricting the flow and causing a back pressure, equivalent to the process pressure, to build up in the system. The P to I converter turns the back pressure into a mA signal, directly proportional to the process pressure. The analogue output means that the PB system can be easily integrated with electronic displays SCADA control and monitoring facilities or PLC's.


Capable of sensing process pressures from a few mm water gauge to 14bar, these sensors are suitable for all kinds of pipes or vessels either pressurised or vented.


The options - The standard version is manufactured entirely in 316 Stainless Steel, with options covering the supply of wetted parts in TITANIUM, INCONEL, HASTELLOY or Stainless Steel coated with FEP, thus providing full compatibility with the product media.




• Series "HF" Air flow regulator


By maintaining a constant differential pressure across a built in pneumatic regulator, the series "HF" is able to provide a set flow of instrument air to the transmitter. The unit is also suitable for bubbler type systems and for purging electrical enclosures in hazardous areas. Constructed in epoxy coated aluminium with treated springs and screws, the unit offers robust performance and a constant air supply to the "PB" transmitters.


• Series H420. P to I converters


CT Holledge H420 instruments are two-wire pressure to current converters. Two models are available for applications where pneumatic signals are required to be converted to current outputs:

H420G - for single pressure inputs

H420D - for differential pressure inputs

Both converters use high performance, solid state piezoresistive sensors, they measure air pressure, or any non-corrosive gas. Output is a proportional 4..20mA




• Diaphragm protection guard - to protect the unit from physical damage.

• Body extension - for lagged or jacketed vessels

• Angled air connectors - allow connections without distorting transmission lines where space is tight.

• Submerged type vent - for use when the "PB" is completely submerged.

• Weather type vent - prevents ingress of rain or damaging particulates.





Rototherm Canongate is a is a leading supplier of process measurement technology for level, liquid concentration and density and Carbon Dioxide.




Company Registration No.:  903846

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