I'm the person who maintains our team's pre-order checklist for industrial gas handling equipment. I started handling equipment orders in 2017. By 2020 I had enough documented mistakes to justify a checklist. In September 2022, I made the most expensive one: I ordered a replacement Howden roots rotary lobe blower by model number only, and it didn't match the actual duty. That one cost $3,200 plus a two-week delay. I've personally made and documented 17 significant mistakes, totaling roughly $46,000 in wasted budget. Most of those could have been caught before the purchase order went out.
If you are about to order a Howden roots rotary lobe blower, a Howden fan, or a Howden refrigeration compressor, this checklist is for you. It is also for anyone who inherited a replacement order and is not sure the original datasheet is correct.
Before the list, let's get two terms out of the way. When I say 'Howden fan,' I mean an industrial fan for process air, boiler draught, or engine room ventilation. I do not mean a leaf blower. If you came here after searching 'leaf blower,' you either found the wrong page or you need a process blower and are not sure what to call it. A Howden fan moves process air—it is not a handheld tool.
Similarly, a Howden refrigeration compressor can be part of an ice maker machine, but 'ice maker machine' is not a specification. The compressor depends on refrigerant, evaporating temperature, condensing temperature, and capacity. If someone sends me a message that says 'Who in the hell put the muffins in the freezer?' I can guess it is a cold store problem, but I cannot pick a machine from it. I have actually seen that exact sentence in an email thread about a refrigeration fault. The muffins were irrelevant; the evaporator was iced up.
Here is the four-point checklist I use before I let a purchase order leave my desk:
1. Confirm the duty before you confirm the model
The September 2022 mistake taught me this in a hurry. The blower had been modified during a previous repair, but the nameplate did not show the change. I trusted the model number and did not write down the duty. The result was a machine that could not reach the required pressure at the required flow. It was not the vendor's fault; it was my missing data.
What most people don't realize is that a model number is assembly identification, not a performance guarantee. The same Howden roots rotary lobe blower model can be built with different rotor coatings, shaft seals, clearances, or bearing types. If you only give the model, you are betting that every previous engineer made the right choices.
I now write down: normal flow, maximum flow, inlet pressure, outlet pressure, gas type, inlet temperature, site altitude. Put another way: the model number tells the vendor which drawings to use; the duty tells them whether those drawings are correct.
'Same as existing' sounds like a shortcut, and I get why people use it. It works when the existing unit is a true clone. At least, that has been my experience. But if the existing unit has been modified, or if the original datasheet was wrong, 'same as existing' preserves the error and hands it to the next person.
2. Check the gas, temperature, and installation location
This is the step that gets skipped most often in real RFQs. I know because I have skipped it myself.
One example: I specified a blower for 'air.' What I meant was process air from an industrial wash line. The air was near saturation and contained a small amount of acid mist. The blower ran, but the carbon steel internals corroded much faster than expected. It was a data gap on my side, not a Howden product failure.
Gas composition changes material selection. Are you moving clean dry air, combustion air, biogas, ammonia, or humid air? Temperature changes impeller clearances and motor loading. Site altitude changes density, and density changes the pressure that a fan can produce. A Howden fan that works well in a cool clean engine room is a different selection from one in a hot salty location.
I don't have hard data on how many RFQs have a blank or vague gas composition line. Based on our review log, my sense is that it is somewhere around one in ten. That number is only an anecdote, but it is an expensive anecdote.
3. Define the package scope, not just the machine
Another mistake I made was ordering a blower and forgetting the relief valve, silencer, and coupling guard. The blower itself was fine. The package was not complete, and the customer had to source those parts locally. That led to a change order, a late start, and some finger-pointing.
For a Howden roots rotary lobe blower, the scope often includes:
- Driver, coupling, and coupling guard
- Baseplate and grouting instructions
- Relief valve and check valve
- Inlet filter and silencers
- Pressure and temperature instrumentation
- Drain and vent piping
For a Howden fan, the extras may include an inlet box, dampers, expansion joints, inlet screen, or a variable frequency drive. Write down every flange and every auxiliary. I used to assume that the original package's accessories would be included automatically. They are not included unless they are on the purchase order.
4. Verify what arrives and how it is stored
This sounds obvious, but I did not learn it until after a few receiving mistakes. One time, the blower was the right model, but the driver motor was wrong. We caught it on installation day and lost a week. Now I check every nameplate against the purchase order and the approved submittal before accepting the crate. It takes 15 minutes and catches the exact type of human error I keep making. I really should have built this habit sooner.
I don't have a formal count of how many problems this has caught. I want to say it has caught at least four issues in the past year, but don't quote me on that—I do not keep the stats.
Storage matters too. A Howden fan that arrives perfect can suffer after six months outdoors if the bearing housings are not protected and the shaft is not turned. A refrigeration compressor package can pick up moisture in the oil if it sits in a humid place. I once found a fan inlet with the start of rust because the crate had been sitting in a puddle. The desiccant bags were still inside. A crate is not a warehouse.
Final reminders
If you keep only a few things from this:
- Send the duty, not just a model number.
- Name the gas clearly.
- List the whole package scope.
- Check the delivery and protect the equipment before it becomes a storage problem.
Five minutes of verification beats five days of correction. That sounds like a slogan, but I have the invoices to prove it. The checklist has saved us roughly $8,000 in potential rework over the past 18 months—that part I actually track.
One last note: model numbers, available options, and product details change. This reflects my experience through 2024. Verify current Howden datasheets and factory options before you finalize your specification.
