Especially if you’re dealing with a rugged application, you have questions about submersible pumps. We receive a lot of common questions that we’ll begin to address here. We hope that by sharing them with readers, we can make your selection process faster and easier. We’ll also clarifying some issues you may not have thought to ask. We’ll include additional FAQs in future posts.How many starts per hour can a submersible pump handle? Can a cast-iron pump handle more than a stainless steel pump?
Before we delve too deeply into this question, let’s first define what “starts per hour” means. It’s the number of times in an hour that a pump starts pumping and then stops. It’s also known as the “duty cycle”. Both stainless steel and cast-iron BJM pumps are rated for ten starts per hour or fewer.
In a previous blog post, we discussed how stainless steel submersible pumps cure corrosion-related pump problems. In many applications, corrosive liquids combine with other factors, such as high temperatures, hard-to-pass solids, and potentially explosive environments. These require more than a standard submersible stainless steel pump.High Temperature and Heavy-Duty Cycles
Although 316 stainless steel pumps are highly corrosion resistant, they do have some drawbacks. The most significant is that they take seven times longer to dissipate heat than traditional cast iron pumps. Retaining heat for extended periods can lead to premature pump failures when pumping corrosive liquids at elevated temperatures.
Here’s how this damaging chain of events begins. The high-temperature liquid limits the pump motor’s ability to cool itself through heat transfer. As the motor runs hotter, the seal oil begins to break down.
How often does your submersible pump wear out and need to be replaced? Are chronic pump failures taking up too much of your maintenance team’s time? Corrosive materials in the water you are pumping can cause these issues and more. Corrosive fluids are common in many wastewater applications, including chemical plants, food/beverage production, metal plating operations, paper processing, etc. If you’re experiencing more downtime or higher maintenance/repair costs, a stainless steel submersible pump may cure these common headaches.
Many substances dissolved in common wastewater fluids can be highly corrosive when pumps are exposed to them for extended periods. The higher the concentration of these substances in a liquid, the worse the corrosion will be. Some common examples include salt, sodium hydroxide (better known as lye or caustic soda), phosphoric and nitric acids, sodium hypochlorite (bleach), chlorine, peracetic acid, and hundreds of others.