Most are forms of in-line float valves which are used to detect draught dispense gas in pressurized dispense system. Fobs stands for Froth-On-Beer and therefore the primary function is to detect froth or gas in pressurized dispense systems.
Where did they originate?
Fobs Detectors originated in the UK and Ireland in the 1970’s. Their introduction, by the main breweries, was a result of pressure from bar-owners, who were frustrated by the amount of draught beer wasted every time a keg of beer was changed. In response to this demand, the main breweries began working with the existent equipment suppliers to design a product to resolve this problem.
How do they work?
There should be a Fobs Detector installed on every keg in a pressurized dispense system, ideally where the keg is located at a distance in excess of 5 Meters away from the dispense faucet. The primary function of the Fobs Detector is to detect the dispense gas that is propelling the draught product from the keg to the dispense faucet. At the end of each keg the dispense gas travels through the keg and into the in-line Fobs Detector, as the draught liquid level in the Fobs Detector reduces the float drops and shuts-off the supply line from the keg to the dispense tap maintaining perfect draught product from the shut-off seal to the draught dispense faucet. The draught dispense faucet stops pouring due to the lack of dispense pressure and the bar tender knows that the keg needs changing. When a new keg is tapped the dispense gas which is trapped between the new keg and the Fobs Detector is vented off at the Fobs Detector, by the vent valve, and the float is lifted allowing the system to be re-pressurized and bar tender can return to pouring perfect beer.
What do they do?
By maintaining perfect draught product in the draught dispense line to the dispense faucet the Fobs Detector totally prevents any waste, which is usually associated with pressurized draught dispense systems as no gas enters the supply line, so there is no requirement to draw-off gassy/frothy product at the dispense faucet. This means that the bar owner can sell all of the contents of the keg without any waste and therefore maximizing the profitability of each keg of draught product sold. On average a bar owner can save a minimum of 4 pints per keg on an average draught beer run of 20 meters, the longer the run the greater the savings.
What other benefits do Fobs Detectors create?
As the dispense gas is isolated at the Fobs Detector the Fobs Detector prevents the wasting of dispense gas, particularly important where mixed gas systems are used and gas costs are higher. Additionally the Fobs Detector gives hygienic benefits by maintaining an always full draught dispense supply line, the opportunity for bacterial growth is greatly inhibited.