How a 'simple' blower order turned into a package comparison project

In January 2024, our maintenance manager forwarded me a quote for a rotary lobe blower package. I'm the office administrator for a 220-person food processing plant. I handle purchasing for maintenance, facilities, and operations—roughly $1.4 million annually across 11 vendors. I report to both operations and finance. When the quote landed in my inbox, I thought it was going to be a normal capital purchase: get three quotes, check the specs, pick the best price.

I was wrong. Not catastrophically wrong, but wrong enough that I spent three weeks learning more about industrial rotary lobe blowers than I ever expected.

The background: we needed a rotary lobe air blower for wastewater aeration

Our existing blower had been limping along since 2019. By early 2024, it was costing us more in maintenance than a replacement would cost in monthly depreciation. The operations team gave me a one-page spec:

  • Rotary lobe air blower, positive displacement
  • Flow: around 1,100–1,300 m³/h at the operating pressure
  • Discharge pressure: roughly 0.6 bar
  • Continuous duty, 24/5 during production
  • Indoor installation, noise-sensitive area

I sent that spec to six vendors. I got six quotes back over the next two weeks. The lowest one was about 18% below the next closest quote. At first glance, it looked like the obvious choice.

The first red flag: 'package' meant different things to different vendors

From the outside, every quote looked similar. They all said 'rotary lobe blower package' in the description. The reality was that only two of the six were quoting a complete package.

The lowest quote included the blower and motor. That was it. No inlet filter, no silencer, no relief valve, no check valve, no flexible connectors, no baseplate, no belt guard, no controls. When I asked about those items, the vendor said they could be added 'as options.'

I should add that I almost missed this. The quote had a line that said 'standard accessories available upon request.' I read it as a good thing. It was actually a warning that nothing else was included.

It's tempting to think you can just compare horsepower and flow numbers. But a rotary lobe blower package is a system. The blower is one part. The package is what actually runs reliably.

What I started asking for instead of a price

After the first red flag, I asked every vendor for a line-item breakdown. I used the same request for all six:

  • Blower unit: model, speed, flow at actual pressure, motor kW
  • Package components: inlet filter, silencer, relief valve, check valve, flexible connectors, baseplate, belt guard, enclosure
  • Controls: VFD or fixed speed, control panel, compatibility with our PLC
  • Performance data: curve at our operating point, not just catalogue free air delivery
  • Scope exclusions: freight, unloading, rigging, piping, electrical, commissioning, training
  • Warranty: what's covered, what's excluded, wear parts
  • Spare parts: recommended first-year spares and lead times

This changed everything. The lowest quote went from 18% below the next quote to roughly 12% above it once we added the missing components, freight, and startup. The mid-range quote that looked more expensive up front was actually the lower total installed cost.

To be fair, the lowest quote wasn't necessarily a bad vendor. They may have been quoting exactly what we asked for: a blower and motor. The problem was that we asked for a 'package' and assumed everyone defined it the same way.

Ask what’s not included before you ask what the price is.

The turning point: finance asked for total cost of ownership

I had prepared a comparison sheet with the three lowest quotes. I was leaning toward the mid-range option, but I still felt pressure to justify why we weren't taking the lowest bid. Then our finance director asked a simple question: 'What does it cost to install and run for five years?'

That's when I realized my comparison was incomplete. We added estimated costs for:

  • Freight and unloading
  • Rigging and foundation work
  • Piping and electrical connections
  • Commissioning and controls integration
  • First-year spare parts
  • Estimated energy use at our operating pressure

I'm not an engineer, so I leaned on our maintenance lead for the energy estimates. He asked each vendor for performance data at our expected discharge pressure. Two vendors sent curves. One sent a single catalogue flow number. That difference mattered.

I'm still not 100% sure why some vendors avoid sharing performance curves. My best guess is that their standard catalogue numbers look better at lower pressures, and they don't want to get into application-specific calculations. But for a 24/5 aeration blower, that data isn't optional.

The result: we chose the transparent quote, not the lowest one

We ended up going with the mid-range vendor. Their initial quote was not the cheapest. But their line-item breakdown was clear, their exclusions were stated upfront, and they included commissioning in the price. They also provided a performance curve at our operating point and a recommended spare parts list.

The package was delivered in Q2 2024. Installation went smoothly—mostly. We did have one small issue: I forgot to specify our PLC communication protocol in the original quote request. The vendor assumed a different signal type, and we needed a minor change order. It added about a week and a small cost. That was my mistake, not theirs.

Six months later, the blower is running within our expected noise range, and we haven't had an unplanned shutdown. The finance team has the total installed cost documented. Operations is happy. I'm just glad I didn't approve the lowest quote and then have to explain the missing parts later.

What I'd do differently next time

If I were sourcing an industrial rotary lobe blower again, I'd change four things:

  1. Define 'package' in writing. List every component you expect. Don't assume the vendor's definition matches yours.
  2. Ask 'what's not included?' before 'what's the price?' The answer tells you more about the real cost than the headline number.
  3. Request performance data at your actual operating point. Catalogue flow at free air delivery is not the same as flow at 0.6 bar.
  4. Compare total installed cost, not equipment price. Freight, rigging, controls, commissioning, and spares can swing the decision.

That last point is really the whole lesson. A transparent quote that lists all fees upfront may look higher at first. But it's usually the one that costs less in the end—and it's the one that won't make you look bad when the invoice arrives.

If you're doing this without a procurement background, don't feel bad about asking for help. I did most of the comparison manually because I wanted to learn the process. But a sourcing and comparison service like Rotary Lobe Blower Sourcing could have shortened the back-and-forth by getting vendors to quote on the same package scope. The key is that you still review the final exclusions yourself. No service can know your site conditions better than your own maintenance team.

I still don't love capital equipment purchasing. But I've learned to treat rotary lobe blower comparison as a package comparison, not a price comparison. That's made the process a lot less painful for everyone involved.