What to do when your valve information is incomplete
You rarely have every detail when you start. Writing down what you do not know, in a form a supplier can answer, beats waiting until the picture is complete.
Most enquiries are written from incomplete information. The valve is on a cylinder in another building, the person who ordered it last has left, and the only record is a line on an old delivery note. The common response is to delay the enquiry until someone has time to go and look. The enquiry then goes out three weeks late and is still missing two details.
There is a better habit: send it now, and be precise about the gaps. A supplier can work with "outlet designation unknown, photograph attached". A supplier cannot work with a blank, and can be actively misled by a guess.
Three labels that do the work
Write each unknown as its own line, and mark it in a way that survives being copied into someone else's email. Three labels are enough:
UNKNOWN means nobody here has the value. NOT CHECKED means a value exists on a document or a part but nobody has verified it. ASSUMED means someone wrote a value down from memory or inference, and it needs confirming before anything is ordered.
The difference matters. An ASSUMED value that turns out wrong causes a return; an UNKNOWN never does, because nobody acted on it.
The rows that are usually open
Model designation - If you have a partial reading, give it partially: "XF-35" with the last character unreadable is more useful than nothing, and far more useful than a guessed complete designation.
Cylinder thread - If the valve is fitted and you cannot see the thread, say so rather than copying a designation from a similar cylinder.
Outlet designation - If an adaptor is fitted, say that an adaptor is fitted. What you can read may be the adaptor, not the valve.
Working pressure - Cylinder markings and valve markings are different things. Say which one you read.
Quantity and timing - These are rarely unknown, and giving them lets a supplier prioritise the enquiry even while the technical rows are open.
The sentence to add at the end
One line to put at the end of the enquiry, which saves a round trip more often than anything else in this post: "Please tell me which of the unknown rows you need before you can quote, and which you can proceed without."
Suppliers differ on this. Some can quote a shortlist from a photograph and a pressure; some need the exact designation first. Asking which kind you are dealing with turns a vague wait into a specific task.
Marked gaps are fine. Tell us what you know, what you have not checked and what you are assuming, and we will tell you which ones we need.