Reading a data sheet: the fields that decide whether it fits

The figure was on the sheet and you read it, so a part that does not fit is not a delivery problem — it is a reading mistake you pay for twice. Four fields decide it, and all four stand on the item before you order.

Drucktransmitter P10 mit schwarzem Gehäuse und Steckverbinder, Aufdruck IP67 und made in Germany auf dem Typenschild sichtbar

Before you compare

Most wrong deliveries are reading mistakes, not ordering mistakes

The figure was there. It was read as though it meant something simpler than it did — a thread called half an inch, an accuracy without a reference, a housing described as stainless. The part arrives, it almost fits, and the second wait begins.

A data sheet is a technical description the manufacturer can change at any time. It is not a legal document, it promises nothing about an individual batch, and it is not evidence of conformity. Knowing that saves the argument at goods-in about which paper was ever binding.

Our position, plainly: all 114 items carry a structured specification table on the page, with manufacturer, part number and technical values. A downloadable PDF exists for four of them. On shukchok, an open marketplace for industrial goods, that count is not a ceiling — a maker who already maintains PDFs brings them along and keeps them on the item.

Specification table on 114 of 114 items, above the price and without a login
The search matches material designations: 1.4404 returns five hits, 316L two
Where a figure is missing it is missing, not filled in with a plausible one

Slow down here

Four fields worth ten seconds each

They look like the easy part of the sheet. They are the part that decides fit and function.

Material number, not trade name
A number such as 1.4404 identifies a defined composition; "stainless" and "V4A" do not. Where an alloy has to resist a specific medium, the number is the only field that carries the answer.
Thread designation
G, R, Rp and NPT are four different systems, and two of them can be screwed into each other far enough to feel right. "Half an inch" is not a thread — a G ½″ measures roughly 20.95 mm across, not 12.7.
Accuracy and its reference
"0.5 %" without a reference is not a specification. Full-scale and reading-based figures differ by an order of magnitude at the bottom of the range.
Ingress protection
IP is about solids and water only. It says nothing about impact (that is the IK code under EN 62262), nothing about chemicals, nothing about ageing and nothing about explosion protection.

The classic

Four threads that look interchangeable and are not

This single table prevents more leaks than any tightening torque. The decisive column is the last one.

G and R share the flank angle and the pitch, which is exactly why they can be screwed together and exactly why the joint weeps later. NPT has a different flank angle and, in nearly every size, a different number of threads per inch: it engages for the first turns and then jams, often destroying the female thread on the way.
Thread	Standard	Form	Flank angle	Seals in the thread?
G	ISO 228	parallel	55°	No — needs a separate sealing face, a bonded washer or an O-ring
R (external)	ISO 7	taper 1:16	55°	Yes, with a sealing compound or tape
Rp (internal)	ISO 7	parallel, mates with R	55°	Yes, in combination with a taper male thread
NPT	ASME B1.20.1	taper 1:16	60°	Yes — but not with G or R, see the caption

Sechs verschiedenfarbige Uniphos-Gasdetektorröhrchen mit aufgedruckter Skala und Gasbezeichnungen (u.a. H2S, SO2), in einer Hand aufgefächert gehalten

Three figures, read twice

Oversize the range and you buy an error you cannot see

A pressure transmitter spanning 0 to 10 bar with 0.5 % of full scale is off by up to ±0.05 bar anywhere in its range. At a working point of 1 bar that is 5 % of the reading. The same 0.5 % referred to the reading would be ±0.005 bar there. So keep the normal working point in the upper third of the range.

PN and Class do not convert into one another. PN 40 is not Class 300 — a Class figure is defined through a pressure-temperature rating, so the permissible pressure falls as temperature rises, and the ratio between the systems travels along that curve.

And the paperwork is three documents, not one. The data sheet describes a type. The EU declaration of conformity is a binding statement about a directive. An inspection document under EN 10204 refers to the actual material — and its timing is what catches people out.

2.1 states compliance without test results, 2.2 adds non-specific results
3.1 comes from a production-independent department and tests the delivered batch
3.2 is countersigned by your inspector — agree it before manufacture

From goods-in and engineering

Six questions the sheet does not answer on its own

Does an NPT thread fit into a G thread?

No. NPT has a 60° flank angle and, in nearly all sizes, a different thread count per inch than G, which uses 55°. It will start, it will feel tight after a few turns, and it will neither seal nor hold — frequently damaging the female thread. Use an adapter, not force.

What is the difference between 1.4404 and 1.4571?

Both are molybdenum-alloyed austenitic stainless steels of the 316 family. 1.4404 achieves its resistance to intergranular corrosion through a very low carbon content, 1.4571 through titanium stabilisation. That difference matters for welding and for sustained elevated temperatures. Our page on material 1.4404 goes through it in detail.

Is IP67 better than IP65?

Not automatically — the two are not nested. IP65 is tested with a water jet, IP67 with temporary immersion, and these load a seal in different ways. If only one figure is given, only one test was run. "IP65/IP67" means both were.

What does "accuracy 0.5 % FS" mean?

0.5 % of the full-scale value, which is a constant absolute error across the whole range. On a 0–10 bar device that is ±0.05 bar at every point, including at 1 bar, where it amounts to 5 % of the reading.

Why does this valve not carry a CE mark?

That can be entirely correct. Pressure equipment below the thresholds in Article 4(1) of the Pressure Equipment Directive 2014/68/EU falls under Article 4(3), sound engineering practice: it needs adequate instructions and a manufacturer’s identification, and it must not carry the CE mark for the PED. A CE mark from another directive — EMC, ATEX, machinery — may still be present and then stands for that other directive.

Can I get an EN 10204 3.1 inspection certificate?

Not through this catalogue today, and that is precisely where a marketplace differs from a single range: a manufacturer or distributor who issues 3.1 documents lists here and keeps them on the item, so the coverage grows with the suppliers rather than with us. Either way the timing decides — a 3.1 document rests on tests tied to a specific order and has to be agreed before manufacture.

Where the fields bite

Categories in which one figure decides the fit

Two ways in

Compare the specification, not the photograph

Every position carries manufacturer, part number and technical values, and the price stands above them without a login. If you make or trade components yourself, that same table is what your listing needs — and putting it here costs you nothing until something sells.

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