One of the specifications for the flame retardancy for contract curtains in the UK is Contract Curtains – BS 5867: part2: 1980: Type B.
Q: Is this the right one for you to use?
It is normally the responsibility of the interior desinger to determine what specification is required and to agree that with the local fire officer. Sometimes there might not be an interior designer. In that situation it is the responsibility of someone like, for example, the hotel owner. It is NOT THE RESPONSIBILITY OF THE FABRIC COMPANY nor is it the responsibility of the CURTAIN MAKER.
You should also tread carefully. If from your research you decide that the correct specification is BS 5867: part2: 1980: Type B then you are still not all the way there. If you plan to use other materials with your curtain or hang them in a novel way or with some sort of coating then all those ‘extra bits’ are relevant. The fire officer needs to be consulted to see if your method of making and hanging the curtains is OK.
Also note that if you are having your fabric treated by someone like Essex Flameproofing or TEK or Textiles FR then once they have treated the fabric they may well perform an indicative test. However if you are then going on to do unusual things to the fabric whilst making and hanging the curtains then you may have to have the curtain material tested by a testing house – such as TFT Ilkley. IE they test the retardancy and compliance of the made up curtain and not just the raw fabric in laboratory conditions.
If you are unsure of these opinions then please consult your local fire officer for correct guidance.