Dealing with Lime Scale Build Up: A Q&A with Hobart’s Alexander Anim-Mensah

November 27, 2018 by Hobart

Dishwashing

Anyone who’s had some experience with commercial dishwashers has heard about lime scale, and has probably even experienced the white scale building up inside the machine. Lime scale is the deposit of calcium and other minerals left behind when hard water evaporates. The hardness of water is measured in grains of minerals per gallon, and refers generally to calcium and magnesium. The higher the levels of calcium and magnesium in water, the harder the water. When hard water runs through appliances such as hot water heaters and dishwashers, the heat used in the process of running the appliances cause the minerals which are heat sensitive to precipitate out of the water. This can form a chalky film and eventually a caked-up, crusty layer in pipes, in the pump, inside the walls and on wash and rinse arms.

Alexander Anim-Mensah, engineering manager -- Warewash, ITW-Hobart Corp., provides information to help understand how scale, including limescale build up, can affect the performance of commercial dishwashers and how to mitigate the issues.

Q: Who should worry about lime scale build up?

A: Lime scale build up on commercial dishwashers is the result of hard water running through the machine. Different parts of the country experience different water hardness levels, but almost every area has some amount of mineral deposits occurring naturally in the water.

Q: Why is it important to delime a commercial dishwasher?

A: There are basically three reasons why regular deliming practices are important. First, it improves the longevity of machine by preventing buildup that could cause corrosion. Secondly, deliming helps prevent the malfunctioning of key machine components such as sensors, valves, and pumps. Scale buildup in pumps causes them to work harder to push water through the valves, and too much build up leads to corrosion, all of which takes a toll on the overall performance of the machine. Therefore, keeping up with deliming helps maintain consistent wash quality by unclogging scale build up in the wash and rinse arms.

Q: How does the deliming process work in a commercial dishwasher?

A: Lime scale build up, which is mostly calcium and magnesium deposits left from hard water, is mostly alkaline by nature. Therefore, an acidic formula is needed to break up and dissolve the buildup. Commercial dishwashers are equipped with a deliming cycle, which runs a little differently than a regular wash cycle. During this cycle, deliming chemicals are added to the water and the solution made is circulated through the machine. It is important that a little heat is used in the early stage of the process as well, as the lime scale build up could contains fats and oils from leftover food particles bond with the scale. The hot water will release the fats and oils and allow the delimer to react with the scale to break it up and dissolve it in the water.

 

Q: What is the difference between a manual, semi-automatic and automatic deliming cycles?

A: Most commercial dishwashers are equipped with a deliming cycle, whether it’s manual, semi-automatic or fully automatic. In a manual cycle, the operator will look inside the machine his/herself to determine the level of buildup mostly on the heating element. When it’s necessary to run the deliming cycle, the operator will fill the tanks to the appropriate water level, add delimer, circulate the solution through the machine for a given time, and then drain it. Then the tank is filled back with fresh water, circulated run through another cycle to get rid of residual delime solution before it’s ready for a normal wash.

Commercial dishwashers with semi-automatic or automatic deliming function will alert the operator when it’s time to run the deliming cycle. Hobart’s Advansys line of commercial dishwashers include an autodelime function. In this case, it alerts the operator when it’s time to delime, and if the operator accepts to delime, the machine doses the right amount of delimer, circulates the deliming solution for a given time, drains deliming solution, rinses machine with fresh water and put the machine back in service. Hobart has other machines similar to the Advansys line which have a semi-automatic delime cycle. In this case all the operator has to do is to add the delimer when prompted.

Q: How often should the deliming cycle be run on a commercial dishwasher?

A: The frequency of deliming depends upon the hardness level of the water, the water temperature and how much water is cycled through the dishwasher each day. Generally, higher temperatures cause more of the temperature-sensitive hardness to precipitate out of the water as scale. This means with all things being equal, a machine operating at a lower temperature is expected to scale less than a higher temperature one. Also, water softeners can be added to commercial dishwashers to reduce the amount of lime scale build up, which can also reduce the frequency of deliming. This means water softening will increase productivity because of fewer shutdowns to delime machine.

Other factors also play a part in frequency of deliming. While deliming is good, excessive deliming and not following appropriate procedure could be bad for the machine, as most delimers are acidic and can harm the machine if  not used properly. Moreover, some dishwashing chemicals could cause more hardness to precipitate as scale in addition to the heat produced scale.

When installing a commercial dishwasher with an automatic or semi-automatic deliming notification, the operator will program in the results of water hardness. The computer in the machine tracks the amount of water used and alerts the operator when it is time to run the deliming cycle. Deliming at the appropriate frequency, using the right delimer and dose and following the proper deliming procedure can improve the longevity of a commercial dishwasher.

Learn more about Hobart's commercial dishwashers.

Tags: Dishwashing

SUBSCRIBE TO THE BLOG!

Latest Posts


Preparing Your School Dishroom for Summer

May 15, 2024 by Hobart Dishroom

As the school year draws to a close and summer break starts, it's important to properly prepare your Hobart dishmachine for summertime shutdown. Taking the necessary steps will help maintain your commercial dishwasher’s performance and ensure a smooth restart when classes resume. Here's a checklist for your school dishroom staff to follow:

Read More

Albany Unified School District Switch to Reusables with Grant Funding

April 19, 2024 by Hobart Dishroom

In the spring of 2024, a new Hobart CLeN Ventless Conveyor Type Dishmachine was installed in the central kitchen of Albany Unified School District (AUSD) in California, thanks in part to grant funding from StopWaste, a public agency focused on reducing waste in Alameda County. The dishmachine allows the school district to switch from disposable to reusable ware, reducing the amount of waste being sent to the landfill each day by the district’s six schools.

Read More

Labor Savings & Food Safety: Undercounter Dishmachines vs. 3 Comp Sinks

July 07, 2023 by Hobart

Study Shows Undercounter Dishmachines Save Labor & Improve Food Safety

If your food service operation relies on manual washing in a three-compartment sink, upgrading to an undercounter commercial dishwasher can significantly improve labor and resource efficiency, as well as food safety. In a recent field study with a QSR operation using a three-compartment sink versus operation with an LX Undercounter Dishmachine, Hobart engineers found an automated dishmachine provided measurable savings in labor time and water consumption, and drastic improvements in food safety and sanitization assurance.

Read More

Choosing Disposable or Reusable Ware for K12 Food Service

April 01, 2022 by Hobart

Each year, an estimated 7.5 to 8 billion breakfasts and lunches are served to K-12 students across the United States. The type of ware used to serve those meals in some ways is just as important as the food that’s on it, and plays a big role in determining the budget, labor needs and waste management for a food service operation.

Many school systems relied on disposable ware programs during the height of the COVID-19 pandemic, even if they had a reusable ware program before the pandemic. Disposables made it easy to package and deliver to-go meals to students doing remote school and helped address concerns over contamination for on-site education. Now as we emerge from COVID-19 restrictions, K-12 food service is being impacted by additional factors including budgets, availability of supplies and storage space, labor costs, and sustainability expectations and mandates. Many schools are reconsidering their ware programs and making the switch to reusables.

Read More

Even Greener Than Before - Commercial Dishwashers & ENERGY STAR 3.0

July 09, 2021 by Hobart

Effective July 27, 2021, all commercial dishwashers sold with the ENERGY STAR label will have to meet new, more stringent guidelines and testing requirements set by the ENERGY STAR program, a joint program between the U.S. Environmental Protection Agency and the Department of Energy. Hobart is ready with dishmachine models from across our entire product line that are certified to the new standards. 

Read More