Retrotech DM-2A - Manual (Page 51)

Retrotec Energy Innovations, Ltd.
43
DM-2A Mark II 2008-02-22
Appendix B
Glossary of Terms and
Abbreviations
As you learn how to use your gauge and/or consult sections within this guide, you may
encounter abbreviations that you’re unfamiliar with.
• ACH Air changes per hour.
• EfLA Effective leakage area being measured.
• EqLA Equivalent leakage area being measured.
• EqLA/Area EqLA divided by the area that you have input into the Setup menu.
• Flow Calculated flow though the fan.
• Flow/Area Flow divided by the area that you have input into the setup menu.
• Velocity Flow Flow calculated from the velocity and cross-sectional area.
• Velocity Air velocity (requires installation of a pitot tube).
• Door Fan A test instrument that fits into an open doorway in order to pressurize
and enclosure. The result is a measurement of the opening size.
• Envelope The surfaces composed of floor and walls and floors that separate the
test volume from volume surrounding the test volume.
• Equivalent Leakage Area (ELA or EqLA) This is the total size of all opens in an
enclosure. The EqLA value is also referred to as the whole room leakage and includes
leaks through the ceiling and below the ceiling area (BCLA). In CA2001 this is
measured in units of square feet or square meters at a reference pressure in Pascals.
The ELA should not be confused with another EqLA that is often called the EfLA or
Effective Leakage Area. It is very unfortunate that both these ELA’s have the same
acronym of ELA. The EfLA was developed for the US ASTM standard and is smaller
than the EqLA by at least a factor of 0.61 because it uses a discharge coefficient of 1.0.
This EfLA is sometimes referred to as the LBL or Lawrence Berkley Labs EqLA because
it was developed and used by LBL natural air change model that enjoys wide usage.
DM-2A Mark II Dual-Channel Pressure Gauge User Manual
B:
Glossary