Hydratec Inc.

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Standalone HydraCALC (Location)

Button: Calculate Function: Calculation Results Error Type: Pressure Required is negative


When running a calculation, the value for "pressure required" shows a negative value.





There's nothing wrong with the calculation


The  results of the negative pressure is not shown anywhere in the final printout. 


The key is the calc result dialog shows a negative pressure indicating that you NEED -17.5 psi. 


The significant word is NEED. 


You actually HAVE much more than that and it's reflected on the final printout by taking the safety margin at the pump inlet instead of elsewhere between the pump inlet and the supply.

In the results above;

System demand is 51.1 psi

Subtract pump boost of 114.4 psi

Equals the Safety Margin is 63.3 psi

51.1 - 114.5 = -63.3 psi.   Negative value means safety margin. 


The calculation shows the test point pressure of 45.8 psi


Pressure at test (45.8) subract safety margin (63.3) equals Pressure Required

45.8 - 63.3 = -17.5 

This is why the intermediate calc results show the value of -17.5 psi as the value of Pressure Required.

Updated: May 14, 2024, 1:21 p.m. Created: Sept. 15, 2021, 4:55 p.m.