var _rothExpirationTime;

var BumpLogoutTime = function() {
    _rothExpirationTime = new Date();
    _rothExpirationTime.setMilliseconds(_rothExpirationTime.getMilliseconds() + 1170000); //1000 milliseconds * 60 seconds * 19.5 minutes
}

var RothLogout = function() {
    var presentDate = new Date();
    if (presentDate.getTime() > _rothExpirationTime.getTime()) {
        window.location = ('/Account/Logout');
    }
}

BumpLogoutTime();
setInterval("RothLogout()", 20000);