Timer Controlled Valve for Irrigation

#include <Servo.h>
Servo myservo;//servo object to control servo
int potPin = A0;    // select the input pin for the potentiometer

int val = 0;       // variable to store the value coming from the sensor
int timerdelay;

void setup() {
myservo.attach(9);//Servo Connected to Pin 9
}

void loop() {
  val = analogRead(potPin);
if(val<100)
{
timerdelay=5*1000*60://5 Minutes Delay
}
else if(val>=100 && val<=200)
{
timerdelay=10*1000*60;//10 Minutes delay
}
else if(val>200 && val<=300)
{
timerdelay=15*1000*60;//15 minutes Delay
}
else if(val>300 && val<=400)
{
timerdelay=20*1000*60;//20 Minutes Delay
}
else
{
timerdelay = 0;
}
myservo.write(180);//Open the Valve
delay(timerdelay);//Wait for specified delay
myservo.write(0);//Close the Valve
                
}