Pressure monitoring for pneumatic tool air lines The compressor has a gauge. The tool does not. Everything between them — hose, coupler, filter, regulator — can lose pressure without anyone noticing, because the tool keeps running, just not as it should.

Why a pressure drop on an air line is hard to see

A tyre that loses air visibly goes flat. An air line that loses pressure does not do anything visible at all: the tool still turns, the job still gets done, and the loss is paid for in time, in finish quality and in tool wear rather than in a puddle on the floor.

The gauge is at the compressor or at the receiver tank, and the work happens at the end of a hose. Between the two sit a filter, a regulator, several metres of hose and two or three quick couplers. A small loss at each of those is normal, adds up, and is completely invisible from the gauge: the tank holds its pressure while the tool is starved.

Then there is the way tools fail. A die grinder or an impact wrench does not stop when it is under-supplied — it loses torque and speed, and the operator compensates by working longer or pressing harder. Nobody files a complaint about that. The pressure is checked when something breaks, which is the one moment when the reading is already too late to be useful.

Finally, most shops run several drops off one line. One tool with a leaking coupler drops the pressure for everyone downstream, and the symptom — a tool that feels tired in the afternoon — is blamed on the tool.

The range question — read this before specifying

Our standard sensor covers 0–500 kPa gauge (0–600 kPa absolute), which is about 5 bar. That is the whole story, and it decides whether this product is right for your line.

Workshop air commonly runs higher than that. A line feeding pneumatic tools is often set somewhere in the 6–8 bar region, which is above the standard range. There are two honest ways to handle it, and we will say which one applies rather than ship something that reads saturated at the top of its scale:

• Measure downstream of a regulator that is set inside the sensor's range. This is a real measurement of what the tool receives, and for many lines it is the more useful number anyway — but it only works if the tool genuinely runs at that pressure.
• Specify a different pressure sensor. If the line truly runs at 8 bar, the standard part is not the answer and we will say so in the first reply, with what we can offer instead.

So the first question we ask is not about quantity. It is: what pressure does the line actually run at, and where is the measuring point? Send those two answers and the range discussion is over in one message.

What the sensor is, in full

Wireless	Bluetooth 5.1, 2.4 GHz — no receiver required; the phone is the reader
Pressure range	0–500 kPa gauge (0–600 kPa absolute), about 5 bar
Accuracy	±2 kPa
Battery	Replaceable CR1632, average service life about 1.5 years; no re-pairing after a change
Operating temperature	−20…+80 °C
Sealing	IP67
Size	Ø21 × 16 mm

A receiver can be built to order when the data has to reach a controller or a display instead of a phone — serial (UART) or CAN output. That is a different configuration, not a different sensor. Specifications are subject to change; laser marking follows the wheel positions and branding agreed for your programme.

Where it fits, and where it does not

A test bench or a single drop	Fits well: one point, checked by somebody with a phone, no wiring wanted.
A line that moves, or a temporary setup	Fits well: no cable, no power feed, nothing to dismantle at the end of the job.
A shop with several drops off one line	Fits, if the pressure is inside the range: check each drop and find the one that is starving the rest.
Continuous monitoring with alarms in a control room	Not with the phone-only setup. That needs a receiver built to order and an integration into your controller or PLC.
A line running 6–8 bar	Only with a regulator ahead of the measuring point, or with a different sensor — confirmed in writing before quoting.

What it does not do

• It does not find the leak. Pressure tells you that a drop exists; it does not tell you which coupler is hissing. That is still a soapy-water job.
• It does not log while nobody is looking in the phone-only configuration. You check when you choose to check. For unattended logging, ask about the receiver version.
• It does not replace a flow meter. A restricted line and a leaking line can show the same pressure at the tool; only flow tells them apart.

What we need from you

1. The working pressure of the line, and the medium (air is what we are set up for).
2. Where the measuring point physically is — a tee, a spare port, or the end of a hose.
3. Whether a periodic check is enough, or the reading has to be continuous.
4. How many drops, so the pack and the labelling make sense.

Four answers, one reply. If the line is outside what the standard sensor can hold, we will say so — including when that means we are not the right supplier for the project. The related pages below show how the same platform is applied to pneumatic shafts and air receivers, where the range question is just as decisive.