The Maximum Continuous Output Pressure and Maximum Output Flow are important in order to understand how many cutting heads you will be able to run with a pump. These numbers can be used in conjunction with the following “Flow Rate Through an Orifice” chart below to determine the number of cutting heads you can use.
Example 1: 50 HP Pump, 1 Cutting Head, 60,000 PSI, 1.1 GPM water output
|Orifice Diameter (inch)|
You would be at the 1.1 gpm limitation of the pump. If there were any water leaks in your system between the pump and the cutting head, you would likely have a pump “over stroke” situation where the pump would try to cycle too fast attempting to create the required pressure. With modern pumps, there is no harm done if this happens. The pump is simply shut down to protect itself from damage and an error message is displayed for the operator.
Running Two Cutting Heads
Example 2: 50 HP Pump, 2 Cutting Heads, 60,000 PSI, 1.1 GPM water output
If you wanted to run 2 cutting heads, then you would take the 1.1 gpm number, divide it by 2 for a maximum of 0.55 gpm per head. Look for the cell under 60 kpsi that has a number smaller than or equal to 0.55. In this case, under the “60” column you would end up in the 0.51 cell, meaning that one 0.010” orifice would put out 0.51 gpm. The maximum number of heads that you could run with the pump at 60 kpsi would be two (1.1 ÷ 2 = 0.55. 0.55 > 0.51 = OK).
Since the pump design engineers have done most of the hard math already, most users need only refer to an “Orifice Selection Chart” similar to the following, which is usually supplied by the pump manufacturer. Here you would quickly see that for the 50 HP pump, you could use either one 0.014” orifice or two 0.010” orifices.
|Max # Orifices||30 HP||50 HP||75 HP||100 HP||150 HP|