When you receive a new tank, you should always place the regulator on it and mark the pressure reading on the regulator (A new tank should have at least 1000 pounds of pressure).  If there are no obvious leaks, you should leave the regulator on the tank and check the pressure reading one to two hours later.  If the gauge has not moved, you can leave the regulator on the tank.  If it has moved, then either the regulator or the tank is leaking.   Contact Intoximeters Customer Service to get help in identifying the culprit.