You've just pulled a brand new, shiny impeller out of the packaging. It looks great and ready to install. But before you do, take the time to have it balanced. I know what you're thinking, it's brand new! Shouldn't it be balanced already? You'd think, but it's not.
Last week, one of our Service Pros stopped by my office to show me a video he shot of a brand new impeller that was out of balance at 800 rpm. Brand new! He remarked that it was a good thing we didn't just put this on the shelf or ship it to the customer. It's our policy that new impellers are balanced before we ship them off to our customers for reasons just like this.
Impellers rotate at very high speeds. When they're out of balance, they can cause tremendous amounts of damage to a pump. The mechanical seal faces will be out of alignment, causing them to break and leak. The bearings will vibrate and cause damage to the balls and outer races.
I had a pile of questions for our Service Pros after watching this video. Here's they told me:
Why don't impellers come balanced from the factory?
The manufacturer makes an assumption that the impeller will be trimmed. According to our Service Pros, about 90% of the impellers they see need trimming before shipping to a customer. For the manufacturer, it doesn't make sense for them to spend time balancing the impeller if the distributor or end user is going to trim them anyway.
How do you know when an installed impeller is out of balance?
When I asked our Service Pros this question, I expected them to say that the pump would make a lot of noise. Not the case. The biggest tell tale sign of an out of imbalance impeller is vibration.
Can you balance an impeller yourself without the machine?
Balancing an impeller is not a DIY activity. Given the rotation speeds of an impeller, it's best to leave this job to professionals that have the tools and expertise to trim and balance the impeller for a long life.
Can you tell by looking at the impeller if it will be imbalanced?
Generally speaking, no. There's a better chance of the impeller being balanced if grind marks are present. If there are no grind marks on the vanes and backside of of the impeller between the pump out vanes, then the impeller has probably not been balanced.
Our Service Pros highly recommend having a professional balance new impellers. According to them, it costs about $500 to do it, a sound investment when you think about the costs that can pile up after running an impeller that is out of balance (downtime, new seal, new bearings, etc.).
Next time you receive a new impeller, don't assume it has been balanced! Check with a professional to ensure it's safe to install it in a pump. Double checking up front will save you loads of time and money in the long run.
Not sure if your impeller has been balanced? Ask us about it! We gladly provide technical assistance to businesses and municipalities in Wisconsin, Minnesota, Iowa, and upper Michgan.