Basic Documentation
Table Of Contents
- About this Application Guide
- Chapter 1–Introduction
- Chapter 2–Goals of the Laboratory Environment
- Chapter 3–Unique Ventilation Needs of a Laboratory Facility
- Chapter 4–Ventilation Systems Classification
- Chapter 5–Laboratory Facility Exhaust Systems
- Chapter 6–Laboratory Containment Units - Ventilation
- Chapter 7–Room Ventilation, Makeup Air, and Pressurization Control Systems
- Chapter 8–Laboratory Temperature and Humidity Control Systems
- Chapter 9–Laboratory Emergencies - Ventilation System Response
- Chapter 10–Laboratory Ventilation System - Validation
- Chapter 11–Laboratory Ventilation System - Commissioning
- Glossary
- Index
Glossary
stack exit velocity
The speed at which the air exhausted from a laboratory facility is discharged as it leaves the
exhaust stack, normally due to a conical top on the stack. Stack exit velocity should typically
be at least 3,000 fpm to ensure adequate dispersion into the outdoor air and to prevent re-
entrainment into fresh air intakes.
standard air
Dry air at a barometric pressure of 29.92 inches of mercury (Hg) and a temperature of
69.8°F.
standard air condition
Standard air is considered to be at a barometric pressure of 29.92 inches of mercury (Hg)
and at either 0% rh and a temperature of 69.8°F, or at 50% rh and a temperature of 68.0°F. It
is a reference point that enables establishing other physical characteristics such as density,
specific heat, etc.
standard air density
This has been set at 0.075 lb per cubic foot and is approximately the weight of one cubic foot
of air at 70°F and 29.921 inches of mercury (Hg).
standard atmosphere
Air at a pressure of 29.921 inches of mercury (Hg) and at 32.0°F. 29.921 inches of mercury
approximately equals 14.696 psi.
static pressure
Pressure exerted by air on the walls and sides of a duct. The direction of static pressure is
perpendicular to that of airflow in a duct. The static pressure of an airstream will be at its
maximum value when the airflow velocity is reduced to zero by an obstruction in a duct such
as a closed damper.
terminal throw
The actual horizontal or vertical distance an air stream travels after leaving an air diffuser
before the actual air stream velocity is reduced to a specific level (that is, 50, 100, 150, or
200 fpm.)
total pressure
Pressure resulting from the movement of air. The total pressure of an air stream is measured
by taking a measurement from a probe pointed directly upstream and in line with the normal
direction of airflow. The total pressure of a moving air stream in a duct is always higher than
the static pressure of the air stream. As the velocity of the air stream falls, the total pressure
also falls, until the total pressure equals the static pressure at zero velocity.
102 Siemens Building Technologies, Inc.