Best practice would be to input it as an inventory item that can be billed out per job. We do that for R410 refrigerant. Purchase by the tank, then divide by the quantity to give cost per ounce, then mark up as per our policy for retail sales. I would suggest if it is a quantifiable quantity used by job then to do it this way. If it is a negligible amount, then I would consider it shop supplies and consider the cost of it when setting pricing. Hope that helps!
Miranda Melnychuk, RSE
Acclaimed! Heating Cooling and Furnace Cleaning
