For calculation purposes, all dimensions entered into the calculator are assumed to be internal to the vessel. If external measurements are used, this will result in an over-estimate of the refrigerant inventory.
The Head Ratio is the ratio of the compressor’s diameter to its head diameter (twice the individual head dimension). Ellipsoidal heads with a ratio of 2:1 are the most common.
The Horizontal Vessel Length includes the shell length and both heads. The length of a 2:1 ellipsoidal head is ½ the diameter.
The “Normal Operating Level” is used to calculate the operating charge as part of the Maximum Intended System Inventory. The “High Level Alarm Location” is used to calculate the Maximum Intended Inventory of the component. It can either be entered manually or calculated as a percent of the total vessel volume. The high level on a vessel is generally considered to be the height of the high level cutout on most vessels or 100% full in the case of high pressure receivers.
Note: If maximum liquid level is not specified, default maximum level is 80% of vessel diameter.
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