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<center>
HYDRANT FLOW CALCULATOR</center>
<br><font size="2" color="#ff0000">To use this calculator highlight the first box, then enter your new value. Press Tab, the flows will recalculate.  Continue entering new values until all values are correct for this flow.</font>
<table>
<tr>
<td  align="right">
<form Name= "calc">
Static:</td><TD> <input size="5" value="55" maxlength="5" Tabindex="1" type="text" Name="static" onchange="Calculate()"> psi before flowing</td></tr>
<tr><td align="right">
Residual:</td><TD><input size="5" value="35" maxlength="5" Tabindex="2"  type="text" Name="resid" onchange="Calculate()"> psi while flowing</td></tr>
<tr><td align="right">
Pitot:</td><TD> <input size="5" value="15" maxlength="5" Tabindex="3" type="text" Name="pit" onchange="Calculate()"> pitot gage reading</td></tr>
<tr><td align="right">
Diameter: </td><TD><input size="5" value="2.5" maxlength="5" Tabindex="4"  type="text" Name="dia" onchange="Calculate()"> size of hydrant opening (2 1/2"=2.5) or (4 1/2 = 4.5)</td></tr>

<tr><td align="right">
This hydrant is flowing:</td><TD><input type="Text" size="6" Name="flowing" tabindex="-1"> GPM</td></tr>
<tr><td align="right">
At 20 psi this hydrant will flow about:</td><TD><input type="text" size="6" Name="at20" tabindex="-1"> GPM</td></tr>
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<SCRIPT LANGUAGE="JavaScript">
function Calculate() {
var s = document.calc.static.value;

var r = document.calc.resid.value;

var d = document.calc.dia.value;
var p = document.calc.pit.value;

var c = .9;

if (d > 2.5)  {var c = .75};

var xxx = 29.83;

var x = Math.pow(d,2);

var xx = Math.sqrt(p);

var f = (xxx * c * x * xx);
document.calc.flowing.value = Math.round(f);

{
var t = Math.pow((s-20),.54);
var b = Math.pow((s-r),.54);
var fe = ((t / b) * f)
};

document.calc.at20.value = Math.round(fe);

}
</script>