fuchifarm
Bronze Member
I purchased one of the Pto adapters from Skidsteersolutions and was dismayed to find they included 1/2" hose for 25gpm rated motor size 160. Apparently they have undersized hoses for all of their pto systems. They use 1/2" diameter hoses for their 80, 120, and 160 motors. A size 80 motor is specified max flow of 17gpm and size 160 is specified at 25gpm.
I would be suspect of all of their Eterra equipment for proper engineering design.
The maximum recommended flow velocity for the hoses they supply is 25ft/s which is specified for intermittent use. The flow velocity of 1/2" hose at 25gpm is 40.9ft/s. This results in heat buildup in the fluid rapidly at flow rates over 15gpm as there is an approximate 1.5hp heat loss drop at 25gpm across the system hoses and fittings. For constant flow use the recommended velocity is 15ft/s. The temperature rise in the hose derates the pressure rating of the hose. Additionally the excess flow velocity can cause fluid cavitation and back pressure on the system pump resulting in system damage.
I recommend anyone using their pto adapter to use caution and reduce their throttle and limit use to low flow until proper hose sizes are installed. The minimum size hose for their low flow systems should be 3/4" and for their high flow system it should be 1".
I have attached the Normogram from the hose manufacturers technical data sheet. I added the respective lines for the size 80 motor and size 160 motor based off the maximum flow specs on Skidsteersolutions.com website. In red is the maximum flow velocity of 25ft/s and green is the SAE recommended design guideline of 15ft/s.
I just received a message from their customer support stating their engineer reviewed my concern and sees no issues with the supplied hoses.
I would be suspect of all of their Eterra equipment for proper engineering design.
The maximum recommended flow velocity for the hoses they supply is 25ft/s which is specified for intermittent use. The flow velocity of 1/2" hose at 25gpm is 40.9ft/s. This results in heat buildup in the fluid rapidly at flow rates over 15gpm as there is an approximate 1.5hp heat loss drop at 25gpm across the system hoses and fittings. For constant flow use the recommended velocity is 15ft/s. The temperature rise in the hose derates the pressure rating of the hose. Additionally the excess flow velocity can cause fluid cavitation and back pressure on the system pump resulting in system damage.
I recommend anyone using their pto adapter to use caution and reduce their throttle and limit use to low flow until proper hose sizes are installed. The minimum size hose for their low flow systems should be 3/4" and for their high flow system it should be 1".
I have attached the Normogram from the hose manufacturers technical data sheet. I added the respective lines for the size 80 motor and size 160 motor based off the maximum flow specs on Skidsteersolutions.com website. In red is the maximum flow velocity of 25ft/s and green is the SAE recommended design guideline of 15ft/s.
I just received a message from their customer support stating their engineer reviewed my concern and sees no issues with the supplied hoses.
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