Mi-T-M EH-2303-0M30, Руководство оператора

Страница: 7 / 24

7
SAFETY COMPONENTS
FLOW SWITCH
The flow switch prevents the burner from being turned on if there is insufficient water. Proper
water flow causes the magnetic core to be pushed up, causing the reed contact to close. This
contact is interlocked with the main heater contactor.
UNLOADER VALVE
The Unloader allows all of the water delivered by the pump to return to the pump suction
side. If the trigger gun is closed (shut) the valve goes into the “bypass mode”. The pump
runs without pressure. However, the pump may be SEVERELY DAMAGED, due to excessive
overheating, if left running in the “bypass mode” or “Gun-Off” situation for more than 6 minutes.
SAFETY RELIEF VALVE
The Relief Valve prevents the machine from being subjected to abnormally high pressures. If
this situation occurs, the valve will blow off relieving the pressure in the coil. This valve may
also operate if the unloader is adjusted too high.
THERMOSTAT
The built-in thermostat stops the unit from overheating. Maximum temperature of the unit
is 300° F. (150° C) Above this temperature, the thermostat contactor turns off the third set
of heaters.
LOW PRESSURE SWITCH
The Pressure Switch ensures that there is pressure, and therefore there is water flow at the
head of the pump. This control does not operate at less than 3 psi. Therefore if the water is
turned off, the machine will not operate.
HIGH LIMIT SWITCH
The high limit switch is a thermostat which operates at a higher temperature than the
thermostat, about 305° F (150° C). This switch is not adjustable and will only operate when the
other controls fail to keep the water temperature within the normal operating range. This switch
cuts the power to all of the heaters.
FUSIBLE PLUG
The fusible plug is a safety relief device designed to operate at about 380° F. At this
temperature it should only blow off if all of the other safety devices have failed. This is a one
time device and must be replaced if it releases. More importantly, the cause of this blow off
must be determined before refitting the machine.