1. control device with a vapor‑charged power element.

formation of vapor in a liquid line that reduces mass flow compared to the flow of the total liquid at the same pressure differential.

orifice capillary tube, or other device having a restricted passage of fixed size for liquid refrigerant. It restricts flow of vapor of that same liquid to a lower rate of flow with the same pressure difference.

pressure exerted by a vapor. If a vapor is kept in confinement over its liquid or solid so that the vapor can accumulate above the substance with the temperature constant, the vapor pressure reaches a maximum called the saturated vapor pressure. Note: For a specific liquid or solid, at constant volume of vapor above it, the vapor pressure depends only on the temperature.

unit of voltampere reactive power. For a two-wire circuit, the product of the voltage times the current times the sine of the angular phase difference by which the voltage leads or lags the current. VARs and watts combine in a quadrature to form voltamperes.

anything which in concept or in practice is measurable or quantifiable, as a physical variable such as pressure, length, voltage, power, enthalpy, temperature, speed. “Quantity” often means variable but usually refers to an amount or numerical size. “Parameter” can be variable during design but is constant after construction and during use of equipment.

use of varying airflow to control the condition of air, in contrast to the use of constant flow (often) with varying temperature.