function vulinexample()
{
document.langelier.ph.value=7.7
document.langelier.tds.value=20
document.langelier.Ca.value=5
document.langelier.HCO3.value=10
document.langelier.temperature.value=20
bereken()
}

function vulinsea()
{
document.langelier.ph.value=8	
document.langelier.tds.value=34483
document.langelier.Ca.value=400
document.langelier.HCO3.value=140
document.langelier.temperature.value=20
bereken()
}

function vulintap()
{
document.langelier.ph.value=8.6	
document.langelier.tds.value=273
document.langelier.Ca.value=49
document.langelier.HCO3.value=121
document.langelier.temperature.value=20
bereken()
}

function bereken()
{
var ph=document.langelier.ph.value
var tds=document.langelier.tds.value
var Ca=document.langelier.Ca.value
var HCO3=document.langelier.HCO3.value
var phs,Ka2,Ksp,gammaCa,gammaHCO3,I
var temperature=document.langelier.temperature.value

var eenheidCa=document.langelier.eenheidCa.value
var eenheidHCO3=document.langelier.eenheidHCO3.value
var eenheidEC=document.langelier.eenheidEC.value
var eenheidtemp=document.langelier.eenheidtemp.value

if 		(eenheidCa=="1"){Ca=Ca/(40e3)}
else if (eenheidCa=="2"){Ca=Ca/(40e3)}
else if (eenheidCa=="3"){Ca=Ca/(40e3)}
else if (eenheidCa=="4"){Ca=Ca}
else if (eenheidCa=="5"){Ca=Ca*1e-3}
else if (eenheidCa=="6"){Ca=Ca/2}
else if (eenheidCa=="7"){Ca=Ca/2*1e-3}

if 		(eenheidHCO3=="1"){HCO3=HCO3/(61.02e3)}
else if (eenheidHCO3=="2"){HCO3=HCO3/(61.02e3)}
else if (eenheidHCO3=="3"){HCO3=HCO3/(61.02e3)}
else if (eenheidHCO3=="4"){HCO3=HCO3}
else if (eenheidHCO3=="5"){HCO3=HCO3*1e-3}
else if (eenheidHCO3=="6"){HCO3=HCO3/1}
else if (eenheidHCO3=="7"){HCO3=HCO3/1*1e-3}

if 		(eenheidEC=="1"){tds=tds}
else if (eenheidEC=="2"){tds=tds}
else if (eenheidEC=="3"){tds=tds*2.3904*1e6}
else if (eenheidEC=="4"){tds=tds*2.3904*1e3}
else if (eenheidEC=="5"){tds=tds*2.3904}
else if (eenheidEC=="6"){tds=1/tds*2.3904*1e6}
else if (eenheidEC=="7"){tds=1/tds*2.3904*1e8}

if		(eenheidtemp=="1"){temperature=temperature}
else if	(eenheidtemp=="2"){temperature=0.555*(temperature-32)}
else if (eenheidtemp=="3"){temperature=temperature-273}

if(temperature>=80){alert("the temperature has to be smaller than 80 degree Celsius")} 

else{
if(ph&&tds&&Ca&&HCO3&&temperature)
{
I=2.5e-5*tds

with(Math)
{
Ka2=0.0928e-11*temperature+2.2927e-11
Ksp=9.235e-9*Math.exp(-0.0273*temperature)
a=Math.sqrt(I)
b1=(-0.5*4*a/(1+a))
b2=(-0.5*a/(1+a))
gammaCa=Math.pow(10,b1)
//alert("de waarde van gammaCa is: "+gammaCa)
gammaHCO3=Math.pow(10,b2)
//alert("de waarde van gammaHCO3 is: "+gammaHCO3)
phs=-log((Ka2*gammaCa*Ca*gammaHCO3*HCO3)/Ksp)/log(10)

}
lsi=ph-phs

if 		(lsi<0)		{lsindex="Water is undersaturated with respect to calcium carbonate. Undersaturated water has a tendency to remove existing calcium carbonate protective coatings in pipelines and equipment."}	
else if	(lsi==0)	{lsindex="Water is considered to be neutral. Neither scale-forming nor scale removing."}
else if (lsi>0)		{lsindex="Water is supersaturated with respect to calcium carbonate (CaCO3) and scale forming may occur."}

if		(lsi<=2 && lsi>=0.5)	{lsindexcarrier="Scale forming but non corrosive."}
else if	(lsi<0.5 && lsi>0)		{lsindexcarrier="Slightly scale forming and corrosive."}
else if (lsi==0)				{lsindexcarrier="Balanced but pitting corrosionpossible."}
else if	(lsi<0 && lsi>=-0.5)	{lsindexcarrier="Slightly corrosive but non-scale forming."}
else if (lsi<-0.5 && lsi>=-2.0)	{lsindexcarrier="Serious corrosion."}
else							{lsindexcarrier="Serious corrosion"}
								
document.langelier.phs.value=phs.toPrecision(2)
document.langelier.phs.className="blauw"

document.langelier.lsi.value=lsi.toPrecision(2)
document.langelier.lsi.className="blauw"
	
document.langelier.lsindex.value=lsindex
document.langelier.lsindex.className="blauw"

document.langelier.lsindexcarrier.value=lsindexcarrier
document.langelier.lsindexcarrier.className="blauw"
}
else{alert("You have to fill all the boxes with *")}
}
}