Frequently Asked Questions (FAQ)
Q What does Bronkhorst mean by ln/min or ls/min?
A Mass flow should actually be expressed in units of weight such as g/h, mg/s, etc. Most users, however, think and work in units of volume. No problem, provided conditions are agreed upon, under which the mass is converted to volume. Normal conditions (ln/min): a temperature of 0 °C and a pressure of 1,013 bar are selected, and these reference conditions are indicated by the underlying letter "n" in the unit of volume used. The direct thermal mass flow measurement method is always based on these reference conditions unless otherwise requested. Standard conditions (ls/min): here the reference conditions are based on 20 °C instead of 0 °C. Please be aware of this difference, because mixing up these reference conditions causes an error of 7%!
Q How do I calculate a conversion factor?
developed a unique database, consisting of fluid data of over 600 fluids.
Using application software routines various calculations can be made on-line
at our internet site www.fluidat.com
We invite our customers to visit this site for a free registration. Upon receipt of your login deatails you will be able to calculate conversion factors/tables for Bronkhorst thermal gas & liquids flow meters, calculate Kv-values and orifice sizes for Bronkhorst control valves, calculate the pressure drop accross in-line filters and perform calculations relevant to our CEM evaporation system.
Q What are the "wetted parts" of Bronkhorst® gas / liquid mass flow meters & controllers constructed of?
A Standard materials of construction for all instruments is Stainless Steel 316 or equivalent. On request some wetted parts are available in Monel or Hastelloy. Contact factory for more information. Standard seals are Viton® for a gas mass flow meter / controller and Kalrez® for a liquid mass flow meter / controller.
A The selection of elastomeric sealing material for our instruments must be based on chemical resistance at operating conditions. Bronkhorst has gathered a lot of information about the compatibility of various compounds and we can advise our customers accordingly. However, our recommendations must be considered as guidelines for which no guarantees can be given.
Q Which supply voltage and I/O signals are available for Bronkhorst® gas / liquid mass flow meters & controllers?
A Bronkhorst offers a wide variety of possibilities for electrical hook-up and communication. As a standard all mass flow and pressure meters & controllers can be fed with 15 or 24 Vdc. The options for analog input/output are 0-5 Vdc, 0-10 Vdc, 0-20 mA and 4-20 mA (other on request). Digital communication of virtually all product lines are: RS232, Profibus-DP, DeviceNet, Modbus and FLOW-BUS (Bronkhorst fieldbus).
Q How to interpret the data and terminology on Bronkhorst calibration certificates?
A For a better understanding of the contents of Bronkhorst calibration certificates, please click here.