Retrotech DM-2A 用户手册

Retrotec Energy Innovations, Ltd.

DM-2A Mark II   2008-02-22

Appendix B

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