TRAPChecker - Steam Trap Testing

Overview

TRAPChecker is an SDT ultrasound detector for testing steam traps. A contact sensor listens to the signal inside the trap body and reads its temperature, and from those two readings the device answers one question in a couple of minutes: is the trap working normally, blowing steam, or blocked.

What a steam trap does, and why it fails

A steam trap discharges condensate from a steam system while holding the steam itself back, which is what makes the whole steam system efficient. A failure can go two very different ways, and each costs money in a different form:

• Stuck open (blow-through) - live steam escapes into the condensate return without interruption. This is a direct, measurable energy loss: the higher the pressure, the more steam passes through the stuck valve.
• Stuck closed (blocked) - condensate isn't discharged, builds up in the line, and can trigger water hammer when steam moves through it, risking damage to pipework and fittings. Here the loss isn't energy, it's equipment failure.

From the outside, both failures look identical, just a pipe. The difference only shows up in the ultrasonic signal and the body temperature.

TRAPChecker features

Three states, one result

A working trap cycles: a short burst of noise as the valve opens to discharge condensate, then silence. Blow-through is a continuous, intense signal, with the body hot throughout the cycle. A blocked trap is silent even though the inlet temperature is high, meaning steam is arriving but the trap isn't operating.

Condition	Sound	Temperature	Cause
Working	Cyclical: noise/silence	Varies with the cycle	Normal
Blow-through	Continuous, intense noise	Consistently high	Stuck open
Blocked	Silence	High at the inlet	Stuck closed

Diagnostics with no ultrasound background required

The RS2 Needle contact sensor goes on the trap body, and the result appears on a colour OLED display, so the operator never has to interpret a waveform or spectrum. Basic training takes about an hour; testing a single trap takes around two minutes.

Firmware update: streaming screen

SDT updated the Checker series with a streaming-screen mode: a continuous histogram instead of a single reading, useful for borderline cases such as a valve seat chattering mechanically. The update is free and installs through SDT Updater over USB: download the software, connect TRAPChecker, switch it on, the driver installs automatically, and an update wizard walks you through the rest. Once updated, the device has two screen modes, default (a single reading) and streaming, switched with the On/Off button.

Application areas

Industry

• Oil refining - heating systems
• Chemical - reactors and heat exchangers
• Food - sterilisation and cooking
• Pulp and paper - drying

Power generation

• CHP plants and boiler houses - steam pipelines
• Boiler rooms - heating

Manufacturing

• Textiles - pressing and heat treatment
• Pharmaceutical - sterilisation
• Brewing - boiling

Advantages

TRAPChecker does one job, testing steam traps, so it needs no special training and no setup for a particular plant: place the sensor and hear the difference between a normal cycle and a blow-through. In the SDT lineup it's the entry-level, specialised tier for a fleet where you don't also need air leaks, vibration, or electrical checks in the same device; for that broader mix, SDT270 or SDT340 make more sense, with trap testing as just one of several modes.

Role in a reliability programme

TRAPChecker covers the first line: a fast survey across the whole trap fleet. From there the task moves down the chain:

1. TRAPChecker - fleet survey, sorting working traps from suspect ones
2. SDT270 / SDT340 - detailed analysis of the traps flagged, trending, documentation
3. Repair or replacement - fixing the failure by priority of loss
4. Re-check - confirming the fix, typically after 6-12 months

Testing frequency

An annual survey is enough for most systems. High-pressure and superheated steam lines are worth checking quarterly, since both the cost of a blow-through and the water-hammer risk from a blocked trap are higher there. Energy-management standards such as ISO 50001 recommend folding trap testing into a regular energy audit programme.

Economic impact

A typical plant runs 15-25% failed steam traps; without a regular survey programme that share can reach 30-40%. The cost of a single failure depends on steam pressure: a DN25 trap at 10 bar stuck open passes roughly 200 kg/h of steam, and at a thermal energy cost of about 2,000 KZT per Gcal, that's over 500,000 KZT a year in losses from one trap alone. At those numbers, a survey programme typically pays for itself after the first batch of failures is fixed, not years down the line.

Checker Range

TRAPChecker is part of the SDT series of specialised detectors:

• LEAKChecker - air and gas leaks
• LUBEChecker - bearing lubrication
• TRAPChecker - steam traps
• TIGHTChecker - tightness testing
• HATCHecker - ship hatch tightness
• ULTRAChecker - universal ultrasound detector