1. stuffing around a shaft or valve stem to prevent fluid leakage. See also gland.

2. cooling tower packing. See stuffing box.

1. assembly of a starter, contactor, or relay which are wired together with one or more devices (such as a contactor, relay, transformer, terminals, pressure control, etc.) to perform one or more functions of an air-conditioning system; panel may or may not be enclosed.

2. unit of one or more sections of flat material suitable for mounting electric devices.

3. plate or enclosure for mounting control devices.

1. apparent displacement of an object as seen from two different points not on a straight line with the object.

single number figure-of-merit expressing part-load efficiency for equipment on the basis of weighted operation at various partial-load capacities for the equipment; expressed in kilowatts per ton of refrigeration.

1. any relatively small subdivision of matter, ranging in diameter from a few nanometres (as with gas molecules) to a few millimetres (as with large raindrops).

2. any very small part of matter, such as a molecule, atom, or electron. Also known as fundamental particle.

apparent maximum linear dimension of a particle in the plane of observation.

particulate (particulate matter) state of matter in which solid or liquid substances exist in the form of aggregated molecules or particles. Airborne particulate matter is typically in the size range of 0.01 to 100 micrometres. See also atmospheric dust, respirable particles, total suspended particulates.