Troubleshooting Tips
Volute
(Also called High Temp)
WHAT IS VOLUTE?
Irrigation Craft pioneered this redundant safety sensor in 1990 to back up other sensors on the pump station and thereby protect against severe damage to the pump station when other components fail or are mal-adjusted. Volute temperature sensing had been used in pump applications, but not as a redundant safety feature.
The volute is the part of the pump which contains the fluid being pumped, inside of which the impeller spins. Volutes have connections for fluid intake and discharge. In Irrigation Craft pumping systems, VOLUTE is the label given to the flow safety alarm indicating a volute overheating condition. This alarm was formerly called HI-TEMP.
Volute heat sensors take advantage of a simple phenomena. When a pump impeller spins in a fluid, friction from the spinning impeller impacting the fluid molecules develops heat. As long as fluid continually moves through the pump this heat is removed. If however there is no fluid movement through the pump, then this heat accumulates and the temperature of the fluid in the pump rises. Eventually the temperature will rise high enough to damage system components. A volute heat sensor detects this heat rise and shuts down the pump.
A bimetallic thermostat is inserted into the pump volute making direct contact with the fluid in the pump volute. If while the pump is operating fluid temperature rises to 1000 F., a red light labeled VOLUTE will flash on and off. If the pump volute temperature does not fall below 960 F. within 1 minute, the pump will be turned off and will not re-start until the RESET button is depressed. The red pilot light labeled VOLUTE will turn steady on indicating that a VOLUTE alarm has been declared.
POSSIBLE CAUSES OF VOLUTE HIGH TEMPERATURE PROBLEMS:
1. The selector switch was turned to HAND, and the pump left running with no water flowing.
2. ON CLOCK DEMAND SYSTEMS - There is a field problem causing a NO FLOW situation, but the NO FLOW control system is malfunctioning.
3. ON PRESSURE DEMAND SYSTEMS – A failed flow switch or flow limit switch failure. On PRESSURE ON – FLOW OFF type control systems, the flow switch or flow limit switch turns the pump off when water flow stops. If this flow or limit switch fails the pump will not turn off and the volute temperature sensor will then detect the heat rise in the pump volute and turn the pump off.
4. VOLUTE temperature detection system malfunctioning, volute sensor has failed.
NOTE: During hot summer months, the volute temperature sensor will often be tripped during daylight hours when the pump is not operating because volute water temperatures in South Florida can reach 1400 F on hot summer days when the pump is not operating. This is normal. The VOLUTE circuitry ignores the sensor unless the pump is operating, and once the pump starts, a time delay allows the sensor two minutes to be cooled down by fresh cool fluid moving through the pump, before declaring a VOLUTE alarm condition. Years of experience have proven that this design is the best and prevents false alarms.
Testing the Volute Feature
On Irrigation Craft pump stations test the VOLUTE safety system as follows. Turn the HOA selector switch to the HAND mode with the station discharge valve closed. A VOLUTE failure will normally be declared in about 3-5 minutes, but on some systems 10 minutes may be required.
Notes on other Brands
Irrigation Craft tests 100% of our temperature sensors. We have found that this component may not work unless tested 100%.
Some manufacturers have used much higher temperature settings on their volute sensors, sometimes as high as 125 degrees F. This causes two problems: testing is difficult because it takes so long to develop sufficient heat to test the system, and some damage may be done to the pump motor and nearby plastics by the time this higher temperature is achieved.
