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
friction loss (Ventilation Systems)
Consumption or loss of airflow energy as air moves through an HVAC component. The
component can be a length of duct; a duct fitting such as an elbow, junction or takeoff; a
control device such as a damper, heating or cooling coils; ceiling diffusers; or exhaust grills.
Friction loss can be expressed directly in terms of the static pressure loss at a specific airflow
rate (that is, 0.5 inch of water column (in. WC) at 1000 cubic feet per minute (cfm)). For duct
fitting, the friction loss is often expressed in terms of an equivalent length of straight duct of
the same size. Good HVAC system design strives to maintain a low friction loss in the duct
system since this translates into the need for less fan energy and thus lower operating costs.
A well-designed duct system can use smaller components and generate less airflow noise.
Round duct has the advantage since a given length has less friction loss than rectangular
duct with the same internal area.
fume hood static pressure
Negative static pressure measured in the exhaust duct just after its connection to a chemical
fume hood’s exhaust outlet. The static pressure value is measured just a few duct diameters
(normally 2 to 5) downstream of where the exhaust duct connects to the fume hood.
inches of water (inches water column)
A unit for very low air pressure measurement used in HVAC applications. One inch of water
is equal to the pressure exerted by a water column 1 inch in height at 39.2°F. Abbreviated as
in. WC.
Integrated Facility Management System
HVAC control and monitoring system where all local controllers and components
communicate and share information with each other. Other systems, such as fire, security,
card access, and paging, can also be connected to an integrated facility management system
that enables coordinated facility-wide operation, monitoring and control from one or multiple
computer terminals. Integrated systems are typically configured to have at least one
computer based monitoring station that also has a color graphic monitor and the availability
of hard copy printouts for alarm reports and systematic record keeping.
laminar flow
Fluid flow in which all molecules travel parallel to the main direction of flow. This is in contrast
to irregular or turbulent flow in which the molecules move in constantly changing directions
while generally moving in the main direction of flow. Although laminar flow is the most
efficient means of fluid movement, it is very difficult to achieve in real world applications since
laminar flow requires a very streamlined path of movement with no obstructions and limited
velocity. Optimum containment and protection with respect to a fume hood or biosafety
cabinet would be attained with laminar airflow. In actual practice laminar flow is mostly a goal
rather than something actually achieved. In the case of HVAC airflow in ducts, the need to
use elbows, fittings, fans, control devices, etc. generally makes laminar flow unattainable.
98 Siemens Building Technologies, Inc.