Not every high-pressure pH measurement needs a retractable hot-tap assembly. On many pressurised pipelines in Malaysian plants, the line is isolated for maintenance on a planned schedule anyway, and what the measurement point needs is a sensor that simply survives high pressure and temperature reliably between those shutdowns. That is the role of a high-pressure in-line pH sensor such as the ABB TB567 or TBX567.
The LECOL B85 high-pressure pH sensor is LECOL’s equivalent model for this installation. This article explains how a high-pressure in-line sensor differs from a normal pH sensor, how the B85 is built, and what to check when replacing an ABB TB567 in Malaysia.
The short answer is this. A normal pH sensor has a plastic body and a liquid or gel reference that cannot tolerate high process pressure, so it leaks, contaminates or loses calibration quickly in pressurised lines. The LECOL B85 is a two-part sensor, a PPS (Ryton) sensing element inside a 316 stainless steel housing, rated to 20 bar and 135°C, and it uses LECOL’s patented solid-state ION BARRIER reference. It is the LECOL counterpart to the ABB TB567, which uses the same two-piece construction with a Ryton electrode body and stainless steel sleeve.
Why normal pH sensors struggle in pressurised lines
A normal pH sensor is designed for open tanks, low-pressure flow cells and sample lines. When installed directly into a pressurised pipeline, its weaknesses show quickly.
The reference is pressure sensitive. A liquid or gel potassium chloride reference connects to the process through a small junction. When process pressure exceeds the pressure inside the reference, process fluid is driven into the electrolyte, contaminating it and shifting the reference voltage. Pressure fluctuations from pumps and valves make the reading move with pressure as well as with pH.
The body is not built for pressure. Plastic bodies and single seals that are fine at a few bar can creep, crack or leak at higher pressures, particularly when combined with elevated temperature.
The temperature limits are low. General purpose glass and gel references are typically limited to around 60 to 80°C, below the operating temperature of many pressurised process lines.
How the LECOL B85 differs from a normal pH sensor
Two-part pressure construction. The B85 separates the sensing element from the pressure-bearing housing. The PPS (Ryton) sensor sits inside a 316 stainless steel housing that carries the mechanical load of the process, and the assembly installs directly into pressurised systems. The sensor element can be replaced while the housing stays in place.
ION BARRIER solid-state reference. With no liquid or gel electrolyte chamber, there is no liquid volume for process pressure to push sample into. LECOL’s patented reference passes sample through a wood-cell filter and then the ION BARRIER, a matrix of ionic pathways that slows the movement of aggressive ions towards the silver/silver chloride element. The reference is therefore far more stable under high and fluctuating pressure than a liquid or gel design.
High pressure and temperature rating. The B85 is rated to 20 bar maximum and 135°C maximum.
Glass and junction options. The measuring electrode can be hydrofluoric acid resistant, coating resistant hemispherical, high temperature (15 to 135°C, tolerating 140°C temporarily) or platinum ORP. The junction is notched PTFE or notched wood, and PT100 or PT1000 temperature compensation is available.
| Feature | Normal pH sensor | LECOL B85 |
|---|---|---|
| Pressure rating | Typically a few bar | 20 bar maximum |
| Temperature rating | Typically 60 to 80°C | 135°C maximum |
| Construction | Single plastic body | PPS sensor in 316 stainless steel housing |
| Reference | Liquid or gel KCl, pressure sensitive | Solid-state ION BARRIER, patented |
| Junction | Small ceramic pin | Notched PTFE or wood |
| Replacement | Whole sensor | Sensor element only, housing reused |
Replacing an ABB TB567 or TBX567 with the LECOL B85
The ABB TB567 is a high-pressure in-line pH/ORP sensor built as a two-piece sensor with a Ryton electrode body, a 316 stainless steel outer sleeve, Viton O-rings and a wood or PTFE junction, rated to 200 psi at 140°C and 250 psi at 100°C. LECOL identifies the B85 as its equivalent. The construction is closely aligned: both use a Ryton (PPS) sensing element in a stainless steel housing, and both offer wood or PTFE junctions. For plants in Malaysia running TB567 sensors on pressurised pipelines, this makes the B85 a natural fit for the same installation role.
Before ordering, confirm the following against the existing TB567 installation. Autoflo checks these as part of supply:
Process temperature. The B85 pressure rating of 20 bar is well above the TB567 rating at temperature, but its maximum temperature is 135°C, against 140°C for the TB567. If your line runs continuously close to 140°C, confirm the actual operating temperature before selecting the B85.
Housing and process connection. Confirm the thread and installation arrangement of the existing housing. The B85 can be supplied with its own 316 stainless steel housing where the existing hardware is to be replaced.
Glass selection. Select the glass for the process conditions: high temperature glass for hot lines, HF resistant glass where hydrofluoric acid is present, and platinum ORP for redox measurement.
Analyser connection. Confirm the temperature element (PT100 or PT1000) and wiring expected by your analyser, and select a cable length to suit.
When to choose in-line rather than hot-tap
The B85 is an in-line sensor, so removing it requires the line to be depressurised and isolated. For measurement points where the process can be isolated during planned maintenance, this is the simpler and more economical choice. Where the line cannot be interrupted, a retractable hot-tap design such as the LECOL B86 is more appropriate. Reviewing this choice at the time of replacement is worthwhile, because operating patterns at many Malaysian plants change over the life of an installation.
Where the B85 fits in Malaysian industry
The B85 is designed for high-pressure pipelines and other high-pressure applications. In Malaysia, these include process lines in petrochemical, oleochemical and chemical plants, high-pressure process and utility water systems, and power generation, where continuous and reliable pH measurement is needed under conditions a normal sensor would not withstand.
Autoflo Technology is the authorised distributor of LECOL pH and ORP sensors in Malaysia. If you are replacing an ABB TB567 or TBX567 high-pressure sensor in Malaysia, send us the existing model code and process conditions and we will confirm the matching LECOL B85 configuration. Contact us at info@autoflotechnology.com.
Other ABB TB5 series replacements in Malaysia
Replacing a different TB5 model? See our guides to the ABB TB556 pH sensor and the LECOL B65, the ABB TB557 hot-tap pH sensor and the LECOL B75, and the ABB TB564 high-pressure hot-tap pH sensor and the LECOL B86.
ABB, TB567 and TBX567 are trademarks or product designations of ABB. They are referred to here only to identify compatible installations. Autoflo Technology and LECOL are not affiliated with or endorsed by ABB.