Some pH measurement points sit where the process is both hot and highly pressurised: pump discharges, pressurised reactors, high-pressure tank walls. A sensor here must survive the conditions, and it must also be removable without shutting the process down, because a shutdown on a high-pressure line in a Malaysian petrochemical, chemical or power plant is expensive and carefully planned. This is the job of a high-pressure hot-tap retractable pH sensor such as the ABB TB564 or TBX564.
The LECOL B86 hot-tap type high-pressure pH sensor is LECOL’s equivalent model for this installation. This article explains how a high-pressure retractable sensor differs from a normal pH sensor, how the B86 is built, and what to check when replacing an ABB TB564 in Malaysia.
The short answer is this. A normal pH sensor is neither built for high pressure nor removable while the process runs, and its liquid or gel reference is easily pushed, poisoned or depleted under pressure. The LECOL B86 combines a retractable hot-tap design inside a 316 stainless steel extraction housing, rated to 20 bar and 135°C, with LECOL’s patented solid-state ION BARRIER reference. It is the LECOL counterpart to the ABB TB564 for high-pressure hot-tap installations.
What high pressure does to a normal pH sensor
A normal pH sensor uses a liquid or gel potassium chloride reference connected to the process through a small junction. Under high process pressure, three problems appear.
Process fluid is pushed into the reference. When process pressure exceeds the internal pressure of the reference chamber, the sample is driven through the junction into the electrolyte. This dilutes and contaminates the reference, shifting its voltage and accelerating poisoning.
Pressure swings change the junction potential. As pressure rises and falls with pump cycles and process changes, the flow through the junction changes direction and rate, and the reading moves with it rather than with pH.
Mechanical stress. Plastic sensor bodies and seals that are adequate at low pressure can creep, leak or fail when combined with high temperature.
On top of this, a sensor fixed into a high-pressure line can only be removed after depressurising and isolating the line, so every cleaning or calibration becomes a planned maintenance event.
How the LECOL B86 differs from a normal pH sensor
Retractable hot-tap design. The B86 sits in a 316 stainless steel extraction housing fitted with a 1-1/4 inch full-port ball valve. The sensor can be withdrawn into the housing, the valve closed, and the sensor removed for cleaning, calibration or replacement without interrupting the process. The extraction housing has 1/4 inch NPT ports, which can be used for flushing or pressure equalisation.
ION BARRIER solid-state reference. Because the B86 has 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. This makes the reference far less sensitive to pressure and pressure changes than a liquid or gel design.
Robust construction. The sensor body is PPS (Ryton), housed in 316 stainless steel, and the assembly is rated to 20 bar maximum and 135°C maximum.
Junction and glass options. The junction is notched PTFE or notched wood, the latter for oily or hydrocarbon-fouling service. The measuring electrode can be hydrofluoric acid resistant, coating resistant hemispherical, high temperature (15 to 135°C, tolerating 140°C temporarily) or platinum ORP, with optional PT100 or PT1000 temperature compensation.
| Feature | Normal pH sensor | LECOL B86 |
|---|---|---|
| Pressure rating | Typically a few bar | 20 bar maximum |
| Temperature rating | Typically 60 to 80°C | 135°C maximum |
| Removal | Depressurise and isolate the line | Retract into extraction housing while process runs |
| Reference | Liquid or gel KCl, pressure sensitive | Solid-state ION BARRIER, patented |
| Housing | Plastic body | PPS sensor in 316 stainless steel housing |
| Flushing | Not available | 1/4 inch NPT ports on extraction housing |
Replacing an ABB TB564 or TBX564 with the LECOL B86
The ABB TB564 is a high-pressure hot-tap retractable pH/ORP sensor with a retraction housing for safety and taps for flushing or pressurising, and LECOL identifies the B86 as its equivalent. For plants in Malaysia running TB564 sensors on pump discharges, reactors and pressurised tanks, the B86 is intended to suit the same installation type, with the extraction housing available with or without an isolation valve depending on what is already fitted.
Before ordering, confirm the following against the existing TB564 installation. Autoflo checks these as part of supply:
Process conditions at the top of the range. The ABB TB564 is rated to 300 psi (about 20.7 bar) and 140°C, while the B86 is rated to 20 bar and 135°C. For the great majority of installations this makes no difference, but if your process genuinely operates at the very top of that envelope, confirm the actual maximum pressure and temperature before selecting the B86.
Valve and connection. Confirm whether the existing installation has a usable isolation valve and its size and thread, and choose the B86 extraction housing with or without an isolation valve accordingly.
Body material. The ABB TB564 electrode body is Kynar (PVDF), while the B86 uses PPS (Ryton) inside 316 stainless steel. Both are chemically resistant, but confirm compatibility for unusual process chemistry.
Glass selection. Choose the glass for the actual process: high temperature glass for hot streams, HF resistant glass where hydrofluoric acid is present, and platinum ORP if the point measures redox.
Analyser connection. Confirm the temperature element (PT100 or PT1000) and wiring expected by your analyser, and select a suitable cable length.
Where the B86 fits in Malaysian industry
The B86 is designed for high-pressure tank side mounting, pump outlets and other high-pressure applications. In Malaysia, these measurement points are found in petrochemical and oleochemical plants, chemical reactors, power generation and pressurised process water systems, where pH must be measured reliably at conditions a normal sensor would not survive.
Safety comes first with high-pressure retraction
Retracting a sensor from a 20 bar line is a hazardous operation if the procedure is not followed. Before any retraction, operators should confirm the extraction housing is correctly assembled, use the flushing ports to equalise or relieve pressure as the procedure requires, and never stand in line with the sensor during withdrawal. A clear written procedure posted at each high-pressure sensor is the simplest way to make sure maintenance is done safely and consistently.
Autoflo Technology is the authorised distributor of LECOL pH and ORP sensors in Malaysia. If you are replacing an ABB TB564 or TBX564 high-pressure hot-tap sensor in Malaysia, send us the existing model code and process conditions and we will confirm the matching LECOL B86 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 TB567 high-pressure pH sensor and the LECOL B85.
ABB, TB564 and TBX564 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.