Fulton Vertical Electric (FT-N) Thermal Fluid (hot oil) Heater - Manual (Page 72)

Fulton Thermal Corp.*Electric Thermal Fluid Heaters Manual* Version 2010-0423
Page 72
compressed air, high-pressure water or a cleaning solution. Replace and
observe new heater inlet pressure.
c) Failed circulation pump coupling
1. A failed coupling will result in a decreased or no flow condition through
the heater. The coupling can be checked by removing the coupling guard
between the pump and pump motor. The coupling should not be torn or
misshapen. If the coupling needs to be replaced, it will be necessary to
re-align the circulating pump first at ambient temperature and again
when it's at operating temperature.
d) Cavitation of the circulating pump
1. Cavitation occurs when a partial vacuum presents itself at the eye of the
pump impeller due to loss of head or if any low heater flashes to gas at
the impeller.
2. During this time, the pump impeller spins without actually circulating any
thermal fluid. If Fulton Thermal Corporation provided the heater skid, loss
of head to the pump is extremely unlikely with proper fluid level in the
tank.
3. The most common low heater in a thermal piping system is water, which
needs to be boiled out at startup.
4. Once the system has been brought up to full operating temperature,
assuming that the entire system has seen flow, there should be no
further occurrence of low heater contamination apart from heat
exchanger failure.
e) High inlet pressure switch
1. Units newer than mid-1993 have a High Inlet Pressure Switch. This is a
normally closed switch that opens with improper heater inlet pressure.
2. The purpose of the High Inlet Pressure Switch is to protect the heater
from building too high of a pressure.
3. Typical electric heaters have a maximum working pressure of 150 psi
with 100 psi safety valve(s) on the heater outlet manifold. The High
Outlet Pressure Switch should be set at 5 psi over the heater outlet
pressure as read at ambient temperature assuming that none of the
conditions mentioned below are true.
Tripped High Outlet Pressure Switch
a) An obstruction downstream of the heater
1. Any obstruction downstream of the heater will increase the pressure that
the heater outlet sees. This obstruction will generally result from an
improper valve setting.