function roundTo(num,pow){
  num *= Math.pow(10,pow);
  num = (Math.round(num)/Math.pow(10,pow))+ "" ;
  if(num.indexOf(".") == -1)
    num += "." ;
  while(num.length - num.indexOf(".") - 1 < pow)
    num += "0" ;
  return num ;
}

function calcForm(frm) {

 // pressure values
 ip = frm.ip.value * 1;
 dp = frm.dp.value * 1;
 iu = frm.iu.value * 1;
 du = frm.du.value * 1;

 // convert pressures to psig
 if (iu==1) { ip*=14.5;  }
 if (du==1) { dp*=14.5;  }
 if (iu==2) { ip*=14.22; }
 if (du==2) { dp*=14.22; }
 if (iu==3) { ip-=14.7; }
 if (du==3) { dp-=14.7; }
 if (iu==4) { ip = (ip*14.5) + 14.7; }
 if (du==4) { dp = (dp*14.5) + 14.7; }

 // flow values
 fl = frm.fl.value * 1;
 fu = frm.fu.value * 1;

 // convert flow to SCFM
 if (fu==1) fl*=.62;
 if (fu==2) fl = fl/60;
 if (fu==3) fl = (fl*2.12)/60;

 // calculate OCR
 ocr = roundTo((dp + 14.7)/(ip + 14.7),1);

 // gas value
 gas = frm.gas.value * 1;

 // ** calc stages bases on gas

 // Oxygen, Nitrogen, Hydrogen, Air
 if (gas==0 || gas==1 || gas==2 || gas==3) {
	if (ocr<=3.5) stg = 1;
	else if (ocr>3.5 && ocr<=12) stg = 2;
	else if (ocr>12  && ocr<=43) stg = 3;
	else if (ocr>43  && ocr<=150) stg = 4;
	else if (ocr>150  && ocr<=525) stg = 5;
	else stg = 999;
	k=1.4;
 }

 // Natural Gas or CO2
 if (gas==4 || gas==5) {
	if (ocr<=4.5) stg = 1;
	else if (ocr>4.5 && ocr<=20) stg = 2;
	else if (ocr>20  && ocr<=91) stg = 3;
	else if (ocr>91  && ocr<=410) stg = 4;
	else if (ocr>410  && ocr<=1845) stg = 5;
	else stg = 999;
	k=1.3;
 }

 // Argon or Helium
 if (gas==6 || gas==7) {
 	if (ocr<=3) stg = 1;
	else if (ocr>3 && ocr<=9) stg = 2;
	else if (ocr>9  && ocr<=27) stg = 3;
	else if (ocr>27  && ocr<=81) stg = 4;
	else if (ocr>81  && ocr<=243) stg = 5;
	else stg = 999;
	k=1.67;
 }

 if (stg == 999) {
 	stg = cr = bhp = bhpp = bhpm = cf = results = "Call RIX";
 } else {
	 // calc CR
	 cr=Math.pow(ocr,(1/stg));
	 bhp = ((Math.pow(cr,((k-1)/k))-1)*(k/(k-1))*fl*stg)/8.8;

	 bhpp = bhp*1.05;
	 bhpm = bhp*.90;


	 if (bhp<=4) cf = "2TX";
     else if (bhp>4 && bhp<=15) cf = "2V";
	 else if (bhp>15 && bhp<=50)  cf = "4VX";
	 else if (bhp>50 && bhp<=150) cf = "2JS";
	 else if (bhp>150 && bhp<=250) cf = "2M";
	 else if (bhp>250 && bhp<=500) cf = "2D";
	 else stg = cr = bhp = bhpp = bhpm = cf = results = "Call RIX";

	 if (cf != "Call RIX") {
		 cr = roundTo(cr,1);
		 bhp = Math.round(bhp);
		 bhpp = Math.round(bhpp);
		 bhpm = Math.round(bhpm);

		 results = "Your approximate power requirement is " + bhpm + "-" + bhpp + " BHP (" + Math.round(bhp * .75) +
			" kW) and you need a " + stg + " stage compressor  (" + cr + " compressions per stage).\n\nWe recommend our " + cf +
			" compressor for this application (click link to the right).  Please call us or e-mail a quote request form if you would like a quotation.";
	}
 }

 // output values
 //frm.ocr.value = ocr;
 //frm.cr.value = cr;
 //frm.stg.value = stg;
 //frm.bhp.value = bhp;
 //frm.bhpp.value = bhpp;
 //frm.bhpm.value = bhpm;
 //frm.cf.value = cf;
 frm.results.value = results;
}

<!--

var google_conversion_id = 1068982676;

var google_conversion_language = "en_US";

var google_conversion_format = "1";

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