Fuel Flowmeter Amplifier

Instruments for the measurement of fuel tank capacity and flow seem to have been made by a number of companies such as Simmonds Aerocessories of London who advertised the product in 1952 and in that year they acquired Firth Cleveland Instruments and as that became the overall company name from 1953 onwards they are found under the Firth Cleveland Instruments name. Elliott Bros purchased Firth Cleveland Instruments in 1961 and continued the brand from the Treforest works where they also made Flowmeters and Test sets for these.
Originally the system would include the Transmitter which sensed the fuel flow in the feed line, an Amplifier which amplified and processed the signal from the Transmitter and an Indicator which gave a read-out in lbs/min. Basic signals are generated by the magnetic rotor of the flow transmitter, signal frequency being proportional to the volumetric fuel-flow. Fed to the integrator, the signal emerges as two distinct outputs in the form of a direct current proportional to rate of flow and pulses proportional in number to the total quantity of fuel passed. The two output signals are then fed to the cockpit instrument, which gives presentations of rate of flow as a needle on a dial, and totalized flow as a digital counter. Corrections for variation in fuel density may be made manually or automatically. By 1964 the Company was offering an Indicator which contained the amplifier/integrator saving weight and gaining- ±0.75% in accuracy. With the new Fuel Flow Test Lab in action the Company was by now a major supplier in fuel instrumentation.

Instruments for the measurement of fuel tank capacity and flow seem to have been made by a number of companies such as Simmonds Aerocessories of London who advertised the product in 1952 and in that year, they acquired Firth Cleveland Instruments and as that became the overall company name from 1953 onwards they are found under the  Firth Cleveland Instruments name. Elliott Bros purchased Firth Cleveland Instruments in 1961 and the Aircraft Engine Instruments Division of Elliotts continued the brand from the Treforest works. This site produced fuel flow equipment such as the ‘Pacitor’ system of Fuel Tank Gauges and Fuel Flow Transmitters. Elliott (Treforest) Ltd also made portable testers for Pacitor capacitance gauging systems and Elliott fuel-flow meters. The former are used with the Beverley, Belvedere, Argosy 660 and long-range Britannia, while the latter are for fuel-flow systems in the refuelling portion of the Valiant tanker and in the Javelin, Buccaneer, Scimitar, Sea Vixen and Sea Venom. The business later transferred to Rochester where new types of fuel measurement and indication equipment was made.

The early Fuel Flow measurement systems comprised a Transmitter, an Amplifier and an Indicator. The Transmitter is a transducer that measures the rate of fuel flowing through it and converts this to an electrical signal to drive a remote Indicator. The signal from the Transmitter required amplification for a long run to the cockpit Indicator but around the 1964 period Elliott Bros were advertising a new combined amplifier/indicator developed to meet the needs of the Trident. The combined unit saved weight and gained ±0.75% in accuracy.

The Fuel flow business was important to Elliotts and a new fuel-flow test laboratory—the most advanced in Europe, if not in the world—was opened at Elliott-Automation's Rochester factory on November 20 1964 by Mr Neil Marten, Parliamentary Secretary to the MoA.

Enclosed in a blast-absorbing concrete emplacement, it was designed to test fuel flow equipment for the new generation of supersonic aircraft where fuel temperature of 150°C or higher would be encountered, and units would be required to operate at rigid standards of accuracy under extreme conditions of temperature (up to 200°C ambient) and in areas of extreme vibration.All controls and observers are in a separate building and several closed-circuit TV cameras give a view of critical parts of the system. Hot water and freon are used respectively as heating and cooling media. The laboratory is suitable for developing flow-measurement systems for supersonic airliners or VTOL aircraft. 

The Laboratory can achieve gravimetric calibration accuracy within an error band of ±0.1% of flow rate under the following conditions:

1. Flow rates from 50 to 120,000 lb/hr through three different bores of pipe.

2. Fuel temperatures from -55°C to +180°C.

3. Ambient temperatures from -60°C to +200°C.

There is also a Vibrator capable of producing a maximum thrust of 500 pounds with frequencies of up to 3,000 c.p.s. for resonance searches.

Mass-flow test measurement is effected by weighing the fuel as it accumulates in a tank mounted on a weighing balance, the whole unit being housed in a sealed container filled with nitrogen.

Fuel measurement systems such as Tank capacity, Fuel Flow rate, Fuel Remaining, Fuel Consumed were all big business for Elliott Bros (and subsequent names) and a snapshot of the platforms to which these were fitted can be gained from one of the Company databases:

AV8B, Buccaneer, Concorde, Dominie, EFA, Fiat Rig, Hawk, HS125, HS146 (BAe146), Javelin, Sea Venom, Sea Vixen, Valiant, Scimitar, P1127, Phantom, Phoenix, Trident, Transall C160, MRCA (Tornado), Finnish Hawk, G222, VC10, RB211 and RJ500 engines.........