Frymaster Super Marathon Series Functional Description cont, Pilot Ignition System, Thermostats

1.1 Functional Description (cont.)

An electromechanical millivolt gas valve regulates gas flow to the burner manifold. Dean millivolt fryers use a pilot ignition system to control burner firing.

Thermopile

Pilot

High-Limit

Gas Valve

Pilot Magnet

Operating

Thermostat

Main Valve Magnet

Functional diagram of a typical millivolt system.

Pilot Ignition System

The pilot ignition system is made up of the pilot orifice, pilot hood, and a thermopile or thermocouple. The pilot serves two purposes: lighting the burner and heating the thermopile/ thermocouple. In operation, the thermopile/thermocouple is in contact with the pilot flame and generates millivolts. The millivolt output passes through a normally closed high-limit switch and energizes the gas valve pilot coil, which in turn opens the pilot valve. If the pilot flame is extinguished, voltage is lost to the gas valve pilot coil and the pilot valve closes.

Thermostats

Dean millivolt fryers are equipped with adjustable operating thermostats. The temperature at which the thermostat opens and closes is adjusted by turning a knob.

Dean millivolt fryers are also equipped with a high-limit thermostat. In the event that the fryer fails to properly control the oil temperature, the high-limit thermostat prevents the fryer from overheating to the flash point. The high-limit thermostat acts as a normally closed power switch that opens when exposed to temperatures above 410ºF (210°C) for CE fryers and 435-450ºF (224-232°C) for non-CE fryers. Once opened, the high limit must be manually reset before operating the fryer.

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