pH sensor drift/blockage? 6 expert selection guidelines

In industrial wastewater treatment or chemical processing, pH is a critical parameter, yet it is often the hardest to maintain. Operators frequently face issues like sensor drift, sluggish response times, and short lifespans (often less than 3 months).

Here is the hard truth: 80% of pH sensor failures are not due to quality, but due to wrong selection.

Whether you are dealing with oily wastewater, strong acids, or high-temperature fermentation, choosing the right specific electrode is key. This guide provides 6 expert steps to help you select the perfect industrial pH sensor and save thousands in maintenance costs.practical and industrial pH sensor selection guidelines for engineers.

What is a pH sensor？

In simple terms, a pH electrode (often called a pH sensor or probe) is an electrochemical sensor that measures the acidity or alkalinity of a liquid.

Think of a pH electrode as a battery.

While a normal battery has a fixed voltage, a pH electrode generates a tiny millivolt (mV) signal that changes depending on the pH of the water it is dipped in. According to the Nernst equation, typically, for every change of 1 pH unit, the voltage changes by approximately 59.16 mV (at 25°C).

Most modern industrial sensors are “Combination Electrodes,” meaning they combine two essential parts into one body:

The Measuring Electrode (The “Nose”):
This is the visible glass bulb at the bottom. It is made of special pH-sensitive glass that interacts with hydrogen ions in the water.
The Reference Electrode (The “Baseline”):
Usually made of a Silver/Silver Chloride (Ag/AgCl) wire floating in an internal electrolyte (KCL solution). It provides a stable, constant voltage against which the measuring electrode is compared.
The Liquid Junction (The “Bridge”):
This is a porous material (ceramic, PTFE, or wood) that allows the internal electrolyte to slowly flow out and make electrical contact with the wastewater.

💡 Why Choose Sino Inst?

Unlike fragile laboratory sensors, industrial pH sensors are built with reinforced bodies and specialized junctions to withstand harsh environments.While generic sensors often fail due to junction clogging or glass breakage, Sino Inst industrial pH sensors are built with reinforced PTFE junctions and impact-resistant glass formulations. We customize the internal structure to ensure your readings stay stable, even in the toughest wastewater or chemical applications.

Don’t risk your process with a fragile probe. [Explore Sino Inst’s Durable glass or plastic-shell pH Sensor Series].

The durability and drift of pH electrodes essentially depend on: glass film+reference structure+interface design+installation conditions.

Now that you understand the basics, let’s dive into why industrial pH sensors fail so often—and how to avoid it with the right selection.”

Why are pH electrodes so prone to breakage in industrial settings?

The most common problem with industrial sensors is interface blockage.
No matter what you see:

Numerical drift
Slow response
Calibration is unstable
It’s broken in three months

90% of them are due to the use of sensor structures that are not suitable for the medium.

So, the correct selection=extending lifespan x improving reliability x reducing maintenance costs.

Types of Industrial pH Sensors

You usually just need to think about two things when choosing the correct sensor: the material and how easy it is to keep.

By the material of the body: glass vs. plastic

Glass Body (The Lab Standard): Best for hot and very corrosive chemicals. They are the fastest to respond, yet they are also weak.
- Best for: chemical processing, reaction tanks, and sterilizing at high temperatures.
- Recommended: [Sino Inst Glass Sensor Series]
Plastic Body (Epoxy / PPS / PEEK): Made to be almost impossible to break. The tough casing protects the sensor bulb from damage, making it the best choice for wastewater, however it normally only works up to 80°C.
- Best for: treating wastewater, using in the field, and swimming pools.
- Suggested: [Sino Inst Durable Plastic pH Sensors]

By Electrolyte: Gel or Liquid

Gel-Filled (Sealed): These units don’t need to be refilled and don’t need any maintenance. Great for internet monitoring when you want to “install it and forget it.”
Liquid-Filled (Refillable): Lets you add more electrolyte, which makes the sensor last longer. Best for clean water or precise lab work.

The Defense Line by Junction

Double Junction: A must-have for effluent from factories. It has two barriers that keep poisons (sulfides/metals) from breaking the reference wire.

PTFE Junction: A big ring with holes in it that doesn’t become clogged up in unclean, greasy water.

Complete selection process for industrial pH electrodes (6 steps in total)

Step 1: Confirm the measurement medium (core)

First, ask yourself three questions:

Is the medium clean or dirty?
- Clean: drinking water, circulating water
- Ordinary: Chemical process liquid
- Dirty: wastewater, papermaking, printing and dyeing, electroplating
Is the medium corrosive (strong acid/strong alkali/solvent)?
Does it contain oil, suspended solids, high solids, or high salt?

Determine the type of sensor foundation based on the properties of the medium:

Medium	Recommended electrode type
Clean water	Standard glass+ceramic interface,such as GRT1030.
Ordinary liquid	gel electrolyte+reinforced junction,such as GRT1120WE.
Sewage/Mud	Open/Large Area PTFE Interface，such as KPT561FW.
Strong acid and strong alkali	Special glass film+Double salt bridge,such as HF1120.
Food and Pharmaceutical	ISFET or High Temperature Glass (Sanitary Type),such as GRT1020PD.

Step 2: Choose the appropriate “junction structure”

The junction determines whether the sensor is blocked, which is the key to its lifespan.

Junction Type	Characteristics	Applicable scenarios
Ceramics	High sensitivity	Cleaning medium
Porous ceramics	slightly better pollution prevention	ordinary industry
Large area PTFE	Strong anti clogging	Wastewater, fiber, grease
Open interface	Least likely to block	High pollution, high viscosity
Double salt bridge	Resistant to ion pollution	High salt and highly corrosive media

Step 3: Determine the type of glass film/sensing element

Determine the type of glass film based on temperature and acidity/alkalinity:

Operating conditions	Glass type
Room temperature (0-60 ° C)	Standard glass
High temperature (60-90 ° C)	Medium temperature glass
Strong alkali pH>12	High pH specialized glass
121 ° C disinfection	High temperature glass/ISFET non glass
Food hygiene requirements	ISFET

Step 4: Confirm the structure of the electrode electrolyte

Electrolyte affects stability and maintenance cycle.

Electrolyte type	Advantages	Scenarios
Gel type	Low maintenance	Most industrial applications
Rechargeable	High stability, long service life	Chemical, strong corrosion
Pressure reference	Strongest anti pollution	High pollution and high-pressure scenarios

Step 5: Determine temperature, pressure, and chemical resistance requirements

Temperature: Is there CIP/SIP available? Is there any temperature fluctuation?
Pressure: normal pressure? High pressure vessel? Do we need a pressurized reference?
Material compatibility: Choose PEEK/PPS/316L/glass shell.

Temperature and corrosiveness are the main causes of glass film rupture and reference failure

Step 6: Determine the installation method

The lifespan of an electrode is 50% determined by the installation method.

Optional installation methods:

Immersion type (tanks or reaction tanks): Install these at a 45° angle and 10 to 15 centimeters below the surface of the liquid to avoid bubble traps and deposits.
Type of flow cell (pipeline on-line): Make sure the flow rate is between 0.1 and 0.5 m/s. If it’s too fast, the glass film will wear down, and if it’s too slow, it will clog.
Sanitary Clamp (Pharmaceutical/Food): Pick a tri-clamp that is smooth so bacteria can’t grow in the sides.
Automatic cleaning or self-purging: This is necessary for sewage, oil, or papermaking. It needs to be cleaned with 5% HCl or an enzyme solution and should not be cleaned with anything that scratches the surface.

Installation should avoid bubbles, deposits, and strong eddies, otherwise the electrode will quickly fail.

Typical Selection Guidelines for Different Industries (Quickly Match)

To make it even easier, here’s a quick-reference guide for common industries—match your scenario to the core requirements.

Industry	Core Selection Points	Recommended Model Features
Municipal/Industrial Wastewater	Anti-clogging + easy maintenance	Open junction + automatic cleaning
Chemical Process	Corrosion resistance + stability	Special glass + double salt bridge + PEEK shell
Food/Pharmaceutical	Sanitary + high-temp resistance	ISFET/high-temp glass + sanitary tri-clamp
Electroplating/Papermaking/Dyeing	High salt + anti-pollution	Double salt bridge + large-area PTFE junction

Common errors in industrial sites (avoid pitfalls)

Even the best sensor won’t last if misused. Below are the most common on-site mistakes to avoid.

❌Replacing industrial electrodes with laboratory electrodes
❌Electrode installation upwards causes bubble trapping
❌Ignore temperature compensation
❌Choosing the wrong junction structure
❌Improper cleaning leads to damage to the glass film

How to extend the lifespan of pH electrodes (maintenance points)

✅Can’t dry it
✅Regular calibration (2-4 weeks)
✅Choosing the correct cleaning method (acid washing/alkali washing/enzyme washing)
✅Avoid sudden temperature changes
✅Regularly check if the interface is blocked

FAQ

The pH electrode is the main part that directly makes potential signs by measuring. It is made up of a glass film and a reference. It’s made up of two main types of electrodes: glass ones and plastic shell ones. The pH probe is a full probe that has temperature correction, a case, a cable, and electrodes. It can be placed where it will be used.

“PH sensors” is the most general name for these devices, and it generally means that transmitters or digital interfaces are included. When picking materials for industry, standard electrodes work fine for cleaning media. Pick better probes for areas with high pollution. Pick digital sensors for tracking from a distance. All of these kinds are in Sino Inst’s electrode line, so it’s easy to find the right one for a range of working conditions.

The most common reason is blockage of the liquid interface (sludge, grease, scaling). Other factors include glass film aging, electrolyte depletion, or temperature compensation failure. Diagnosis: Test response time in buffer solution (normal<10 seconds). Solution: First clean the interface (soft brush+detergent or 5% HCl), if ineffective, replace it. Prevention: Choose open or PTFE large-area junctions for high pollution media, with automatic cleaning.

Choose models with dual liquid interface (ceramic+PTFE), PTFE material is non sticky and can reduce impurity adhesion. In daily use, gently wipe the liquid interface surface with a soft cloth every week to avoid scratching with a hard brush. If it is already blocked, soak it in warm water at 30-40 ℃ for 10 minutes, then gently blow through the liquid interface channel with compressed air, and it can be restored without disassembling the machine.

There are three main types of core reasons – electrode surface contamination (biofilm, oil contamination), expired buffer solution/improper calibration operation, and electrode aging (lifespan exceeding 1-2 years). The quick correction steps are simple: first clean the electrode with warm water and dilute hydrochloric acid and calibrate it to ensure that the calibration solution is within its validity period; If it is still inaccurate, check if the temperature compensation is turned on (every deviation of 25 ℃ will result in a 0.003pH/℃ error), and replace the aging electrode directly.

Never allow the electrode to dry out
Clean it regularly based on the process medium
Avoid rapid temperature changes
Install it away from air bubbles and heavy sediment
Use the correct junction type for the application

Proper selection and maintenance can extend electrode life from a few months to over a year.

The main cause of broken glass membranes and evaporated electrolytes is thermal shock. Regular glass begins to break down when the temperature exceeds 80°C. Pick ISFET non-glass electrodes or glass that can handle heat and can work at temperatures up to 130°C. In a pharmaceutical CIP application, a sensor that was standard broke in less than a week. Don’t let the temperature change too quickly, and pick models that can handle high temperatures to keep things from going wrong.

It will be much shorter! High temperatures and strong alkalis will speed up the aging of glass film. In these cases, the life of the electrode will normally go from the normal 6 to 12 months to just a few weeks to months. It is best to use a special model that can handle high temperatures and strong alkalis (such the one with anti-aging glass film and special electrolyte) and cut the calibration cycle down to 2–3 weeks. Also, don’t keep electrodes in high-temperature media for lengthy periods of time, and construct a bypass to cut down on losses.

Choosing the proper industrial pH electrode for the job can save you from having to go to the site a few times, change the probe a few times, and deal with hassles from drifting and clogging.

Please feel free to get in touch with Sino Inst at any time if you are choosing a specific project or want to learn more about industrial pH electrode solutions that last a long time and don’t get clogged. We can give you specific quotes and suggestions based on the type of media you have, the temperature, and the conditions of the installation.