Thermal Protection & Continuous Duty Operation
The shaded areas in both the Performance Data and Heat Rise charts indicate pump models with operating current levels capable of continuous operation without periodic cool-down cycles. Pumps within this range will generally transfer more water over extended periods than pumps operating in the unshaded areas, which require shutdown periods for motor cooling.
Some applications, however, require maximum flow at high pressure for shorter durations. The following information explains the thermal protection considerations for these operating conditions:
1. Continuous Duty Operating Range
The Heat Rise graph identifies the highest current level that can operate continuously while remaining within the shaded area. In this case, the maximum continuous-duty current is 9.50 amps.
All pump models operating below this current level may run continuously, provided the surrounding ambient air temperature does not exceed 70°F (21°C).
2. Maximum Output Model Example
The second curve shown represents the highest flow and pressure model offered: the 55X3.
- At 70 PSI, the 55X3 delivers:
- 3.0 GPM
- 18.00 amps current draw
3. Thermal Protection & Surface Temperature
The motors used in these pump models do not include built-in thermal limiting protection. Users must monitor operating conditions and understand the effects of exceeding the recommended maximum surface temperature of 150°F.
Based on the heat rise data:
- Starting from room temperature, the 55X3 reaches the recommended shutoff temperature after approximately:
- 8 minutes of continuous operation
- Pumping approximately 24 gallons of water at 70 PSI
4. Cooling Requirements
Motors of this size and construction typically require:
- Over 40 minutes to cool to approximately 120°F, where restarting is considered safe
Lower-current models heat more slowly and allow longer operating periods; however, typical cooldown time still averages approximately 30 minutes.
5. Cycling Recommendations
Certain applications may involve short bursts of water usage well below the 8-minute sustained runtime limit.
Keep in mind:
- Startup current exceeds normal running current
- To prevent excessive motor stress, cycling frequency should be limited to:
- No more than 6 starts per minute
Important Notice
All performance and heat rise figures are approximate. Actual operating values will vary depending on ambient temperature and environmental conditions.