German term (edited): Bm³/h

From what I see with google, Bm³/h and its cousin Nm³/h apper to be home-made abbreviations (presumably Betriebs-m³/h and Norm-m³/h).

As the common term for the latter in English is 'standard cubic meters per hour' (SCMH) or 'standard cubic feet per hour' (SCFH), I'd suggest using 'actual cubic metres per hour' (or 'actual cubic feet per hour' in the US), but with a note indicating that it is measured at operating pressure.

refs (the first link apparently only works for the google search engine):

Mankenberg enquiry for overflow valves
Nm3/h = cubic metres at atmospheric pressure Bm3/h =cubic metres at operating pressure (please state pressure). My medium. description. viscosity ...
www.mankenberg.com/produkte/ ueberstroemventile/anfrage-gb.htm
ACFH - Actual Cubic Feet per Hour. The actual volume of fluid measured by the meter. This is not scfh (standard cubic feet per hour).
http://www.ivesequipment.com/customer/iveqco/Principals/AMCO...

standard cubic feet per hour. Cubic feet per hour flow at standard atmospheric conditions at 14.7 psia, 70 degrees Fahrenheit.
http://www.fairchildproducts.com/ic/glossery.asp

SCFM - Standard Cubic Feet per Minute

It is common to rate the compressed air consumption in Standard Cubic Feet per Minute - SCFM.

The SCFM - Standard Cubic Feet per Minute - determines the weight of air to fixed or "Standard" conditions. There are several definitions of SCFM. The most common used in the United States is with "sea-level" properties:
14.696 Pounds per Square Inch (psia)
60 Degrees Fahrenheit (oF) (520oR)
0% Relative Humidity (RH).

Europeans normally use one ata and 0oC as SCFM.

ACFM - Actual Cubic Feet per Minute
Unfortunate real life "actual conditions" are seldom "standard conditions". Actual air volume flow is often termed ACFM - Actual Cubic Feet per Minute.

Actual Cubic Feet per Minute - ACFM, depends on the
pressure
temperature
humidity

of the actual air.
http://www.engineeringtoolbox.com/scfm-acfm-icfm-d_1012.html

STATE OF DELAWARE
DEPARTMENT OF NATURAL RESOURCES AND ENVIRONMENTAL CONTROL
SUPPLEMENTAL INFORMATION FOR AIR POLLUTION CONTROL DEVICE (APCD)
FABRIC FILTER OR BAGHOUSE
AQM-4d INSTRUCTIONS

Provide the design inlet volume of the device. If you are using the electronic form, the drop-down box allows you to choose units of standard cubic feet per minute, standard cubic feet per second, standard cubic meters per minute, or standard cubic meters per second. Standard operating conditions are 1 atmosphere of pressure and 70 °F.
www.dnrec.state.de.us/.../ Permit%20Application%20Instructions%20(AQM-4)%5CAQM%204d%20Instructions.doc
Provide the volume of gas that is cleaned by the device. If you are using the electronic form, the drop-down box allows you to choose flow units of actual cubic feet per minute, actual cubic feet per second, actual cubic meters per minute, or actual cubic meters per second, and temperature units of ºF, ºC, ºR, or ºK.