function calc(form) {

	var nCoef=document.pressuredrop.nC.options[document.pressuredrop.nC.selectedIndex].value;
	if (form.flow.value.length==0||form.length.value.length==0) {
		alert('Please fill out Flow and Hose length to calculate!'); 
		if (form.flow.value.length==0 ) { document.pressuredrop.flow.focus(); } 
		else { document.pressuredrop.length.focus(); }
	} else {
		//if (form.qtyCoupl.value.length==0) { howManyCouplings(form); }
		var iD             = document.pressuredrop.nC.options[document.pressuredrop.nC.selectedIndex].value;
		var stromHastighet = (form.flow.value/(6*(iD*iD)*(3.141592654/4)))*100;
		var Reynold        = (stromHastighet*iD/1)*1000;
		if (Reynold <= 2300) {
			var friktion = 64/Reynold;
			var frMsg    = "Flow is laminar";
		} else {
			var friktion = 0.316/(Math.sqrt(Math.sqrt(Reynold)));
			var frMsg    = "Flow is turbulent";
		}
		form.pDrop_hose.value     = Math.round(10*friktion*((form.length.value*0.99823*(stromHastighet*stromHastighet)*10)/(iD*2)))/10 + " bar";
		form.wSpeed.value         = Math.round(100*stromHastighet)/100 + " m/s";
		form.ReynoldsNumber.value = Math.round(Reynold);
//		alert("The following values was calculated:\n\nWater speed: " + stromHastighet + " m/s\nReynolds number: " + Reynold + "\nFriction: " + friktion +"\n\n" + frMsg);
	} 
}

function howManyCouplings(form) {
	if (form.qtyCoupl.value.length==0) { 

	var temp=document.pressuredrop.nC.options[document.pressuredrop.nC.selectedIndex].value;
	var lHP;

	if (temp==19) { lHP=20; }
	if (temp==12) { lHP=40; }
	if (temp==9) { lHP=10; }
	if (temp==6) { lHP=5; }

	form.qtyCoupl.value=Math.round(form.length.value/lHP);
	}
}