The Differences Between Contacting and Non-Contacting Industrial pH Meters

Industrial pH meters are widely used in various processes such as wastewater treatment, food production, pharmaceutical manufacturing, and many more. Most industrial processes require accurate pH measurements for process control, product quality control, and regulatory compliance. However, choosing the right type of pH meter for a specific application can be challenging, as there are two main types of pH meters: contacting and non-contacting. In this article, we will explore the differences between contacting and non-contacting industrial pH meters to help you make an informed decision.

What are Contacting pH Meters?

Contacting pH meters, also known as immersion or submersion pH meters, are the most common type of industrial pH meters. As the name suggests, contacting pH meters require direct contact with the sample to measure its pH. This type of pH meter consists of a glass electrode (sensing element) and a reference electrode (a cell filled with an electrolyte) connected to a pH meter controller through a cable.

Contacting pH meters are suitable for measuring the pH of liquids, including corrosive, abrasive, and viscous samples. They are widely used in chemical processing, petrochemical, and pharmaceutical industries, where harsh chemical environments can damage the pH sensor. Contacting pH meters are also useful for monitoring processes where the sample is constantly flowing, such as wastewater treatment and food production.

Advantages of Contacting pH Meters:

1. Accurate and reliable measurements: Contacting pH meters offer high accuracy and precision when measuring the pH of liquids, thanks to the direct contact between the sample and the sensing element.

2. Suitable for a wide range of applications: Contacting pH meters can be used in many industries and applications, from simple laboratory procedures to complex industrial processes.

3. Durable and long-lasting: Contacting pH meters are designed to withstand harsh chemical environments and can last for years with proper maintenance and calibration.

Disadvantages of Contacting pH Meters:

1. Sample contamination: Contacting pH meters require direct contact with the sample, which can cause contamination if the sample is not clean or properly prepared.

2. Maintenance and calibration: Contacting pH meters require regular calibration and maintenance to ensure accurate readings and optimal performance.

What are Non-Contacting pH Meters?

Non-contacting pH meters, also known as in-line or flow-through pH meters, do not require direct contact with the sample to measure its pH. Instead, they use a sensing element that is placed outside the sample container, such as a pipe, tank, or vessel, to measure the pH of the sample.

Non-contacting pH meters come in two types: optical and ion-selective electrode (ISE) pH meters. Optical pH meters use light to measure the pH of the sample, while ISE pH meters use a membrane that selectively binds to certain ions, such as hydrogen ions, to measure the pH of the sample.

Non-contacting pH meters are suitable for measuring the pH of corrosive, abrasive, or viscous samples without contaminating the sample with electrodes. They are widely used in the water treatment, pulp and paper, and food and beverage industries, where the sample is constantly flowing.

Advantages of Non-contacting pH Meters:

1. No sample contamination: Non-contacting pH meters do not require direct contact with the sample, which eliminates the risk of sample contamination and reduces maintenance.

2. Suitable for harsh environments: Non-contacting pH meters can withstand extreme temperatures, pressures, and chemical environments.

3. Easy to install: Non-contacting pH meters can be installed in-line with the sample flow, making them easy to integrate into existing processes.

Disadvantages of Non-contacting pH Meters:

1. Less accurate measurements: Non-contacting pH meters may not provide as accurate measurements as contacting pH meters, especially when measuring low-conductivity samples.

2. Costlier: Non-contacting pH meters are generally more expensive than contacting pH meters due to their advanced technology and design.

Conclusion:

Choosing the right type of industrial pH meter depends on the specific requirements of your application. Contacting pH meters are suitable for measuring the pH of liquids in harsh chemical environments, while non-contacting pH meters are suitable for measuring the pH of samples that cannot be contaminated. Both types of pH meters have their advantages and disadvantages, and it is important to evaluate the accuracy, reliability, cost, and maintenance requirements of each before making a decision.