More pH Probe Care and Usage Guidance

An interesting article on practical pH probe care was published in Water and Wastes Digest recently. It intrigued me enough to call one of the authors: Kareem Kay. He is the process reliability manager for Endress+Hauser who manufactures industrial pH equipment. Here are some key points from that conversation.

Temperature and temperature stress are probe killers. Temperature above 80C (175F) is a sure killer. In addition, shocking the probe with quick shifts from cool air to hot wort and back, is also a killer. Kareem confirmed that the recommendation to test only room-temperature wort is a good practice for long probe life.

Sometimes, the probe's bulb can get dirty. Don't touch the bulb with anything more than a soft bristle brush. He also pointed out that an acid soak or a detergent cleaning with the brush can restore a probe's performance. I will add that enzymatic detergents are probably best in brewery use since they are well-suited to working on the protein films that wort may produce.

Keeping the probe wet was a big point for him. If the bulb dries out, it does affect the performance. But he goes on to say that you might be able to rejuvenate a dried out probe by soaking it in potassium chloride solution. In fact, he further identified that his preferred probe storage solution is a 50/50 mixture of 3 molar KCl and pH4 calibration solution. Interestingly, that produces a 1.5 molar KCl solution that falls within the 1 to 2 molar storage solution that I have recommended in the past.

He did admit that the type of usage has an impact on a probe's lifespan. Some use can kill a probe in a couple of days, while other usage could allow a probe to last up to 6 years. My experience is that brewery use with proper sample cooling and probe storage will give at least a year's life and homebrewers could approach that 6 year lifespan.

Remember that the probe's bulb is glass and you can easily break it if you abuse it or drop it. Treat the probe like it is the fragile 'light bulb' that it is and you should be able to maximize your equipment investment.

Enjoy!