// Tank cubic foot to liters converter

function tank_volume() {
var reserve = 40;// The reserve
var capacity = (document.form.cp.value);
var pressure = (document.form.pr.value);
var units = '';
for (var i = 0; i < document.form.un.length; i++) {
	if (document.form.un[i].checked == 1) {
	   units = document.form.un[i].value;      
	}   
}
var operator = (units == "cf")?"*":"/";
var total_liters = eval(capacity * 28.3);
var internal = eval(total_liters/pressure);
var internal = new String(internal);
array_liters = internal.split(".");
array_liters[1] = array_liters[1].substr(0, 3);
internal_liters = array_liters[0] + '.' + array_liters[1];
var liters_available = eval(total_liters - (internal_liters * reserve));
document.form.internal.value = internal_liters;
document.form.pumped.value = total_liters;
document.form.reserve.value = liters_available;
}

function air_required() {
var depth = (document.form.depth.value);
var time  = (document.form.time.value);
var rate  = (document.form.rate.value);
var result = eval((depth/10+1) * time * rate);
document.form.required.value = result;
}