Perhaps the question should be about Volume as opposed to fast or slow flow of water. A higher volume of water delivered to the glass with less speed particularly when rinsing would be useful. A fast flow of water hitting the glass may lead to water splashing and pulling dirt from above the rinse area. I can see how a higher water volume can be of benefit in terms of how quickly a window can be cleaned.
so would you say a higher cal no and a lower psi number
Good Question. In Theory both the calibration and PSI in the system would be lower.
The calibration number does not have a direct impact on the pressure in the WFP system it has much more subtle impact.
Some of the main drivers for pressure in a system are
Pump
Hose and expansion rate of the hose wall
Jet size
By Calibrating a control to a pump and system we are telling the control what the base line pressure in a system is plus what the maximum normal operating pressure is.
From these the control can monitor system pressure and as water is stopped DE the pump.
Increasing the water Volume could mean simply changing the number or size of the jets on the brush head. A wider jet could reduce the amount of pressure as there is less of a restriction.
This would mean the base line pressure is lower to compensate the Calibration needs to be more sensitive and would also be lower.
The question for me is is it better to have maximum flow always EG fast moving water or is it the amount of water on the window together with a means to alter volume that is important?