F-Gas legislation states that if a structure has more than 500 tonnes of gas, then you have to have an expert solution performed a minimum of four times a year. https://w.smokys.com/index.cgi?token=1167101933&action=state&state=redirect&datanum=487&page=white-null.htm&site=http%3a%2f%2fmy.Sterling.edu%2FICS%2FAcademics%2FLL%2FLL379__UG12%2FFA_2012_UNDG-LL379__UG12_-A%2FCollaboration.jnz%3Fportlet%3DForums%26screen%3DPostView%26screenType%3Dchange%26id%3D1a1f088d-9220-4a77-af27-0d4aedda3104