This guideline primarily covers methods to estimate refrigerant mass flow rates and total refrigerant losses during accidental releases involving industrial refrigeration systems. Though the guideline was developed for use in estimating refrigerant releases primarily associated with ammonia refrigeration systems, the methods described are equally suitable for estimating refrigerant release rates associated with other natural refrigerants such as hydrocarbons. Selecting the appropriate equations or computation methods to estimate the mass flow rate associated with a refrigerant release requires detailed knowledge of the leak and the conditions including but not limited to:
Type of refrigerant;
State of refrigerant within the system: saturated liquid, subcooled liquid, vapor, or two-phase;
Refrigerant temperature and pressure;
Geometry of leak opening, e.g., analogous to orifice, nozzle, or pipe flow;
Size of leak opening;
Duration of leak; and
Changes in system dynamics, such as changes in pressure and temperature.
This guideline includes both vapor-phase and liquid-phase (flashing and non-flashing) refrigerant leak rate calculations that are relevant to industrial refrigeration systems. The geometry of the leak location is limited to orifice-type flow, nozzle-type flow, and pipe-type flow, for example, openings that can be described as a round hole or holes described with an equivalent geometric diameter. Complex geometries such as cracks, seals, packing glands, etc., are beyond the scope of this guideline. Though this guideline does not explicitly cover release situations involving two-phase flow, pipe sections and system components with two-phase flow can commonly be treated like single-phase scenarios by determining if the leak site is located so as to entrain the refrigerant in a gas phase or liquid phase.
Purchasers of the guideline will have access to a computer calculation program that aids the user in quickly determining an estimated release quantity. Users of the program are encouraged to be trained on its use. An online training course is available to purchasers and IIAR members. When digital books are purchased, access to download the estimating program and installation instructions is provided on the IIAR/Gilmore Global evantage website (look for the paper clip icon). When hardcopy books are purchased, a USB drive with the program and instructions loaded onto it will be sent with the hardcopy books.