What you should know when commissioning a custom fan

Online Editor

Matt Shelley describes the art and ease of specifying custom fans – and how to get it right

For businesses across the world, finding the right fan for a specific application can be more challenging than you might at first think. Off-the-shelf solutions have their place; an instant solution to an immediate problem. However, this ‘easy’ option can often be surprisingly costly in ways you might not expect.

Get the specifications wrong and you could miss out on considerable cost savings and energy efficiencies, making operations less efficient or competitive. For OEMs providing solutions to the oil & gas market, it could make the difference between product success and failure.

Order a fan that’s too small and it won’t be up to the job. Too large and the excess cost in energy alone could more than double the long-term cost of an off-the shelf option. So, how do you avoid falling foul of fan procurement failure? And how can you be certain of getting a fan that’s just right for the job and at the right price too?

Thankfully, the answer lies in custom-built fans; a precise solution to precise needs, ensuring optimal efficiency and performance alongside considerable lifetime unit cost savings. And the good news is that the process is a lot easier and quicker than you might think.

What information do manufacturers need to build a custom fan?

The first point to note is that a full picture or a complete specification is not necessary at the start. If the airflow and/or pressure (static or total) that needs to be achieved is known, and also the ATEX/IECex specification (if applicable), and electrical supply as a minimum, the process can begin.

If you know the problem that you’re facing – and the outcome that you’re after – your fan manufacturer should be able to put the pieces of the puzzle together to design the perfect fan solution for the job.

From concept to production, working with an accredited fan manufacturer means that you can look forward to a total solution addressing performance, appearance, size, preferred materials, finishes, motor types, speeds, voltages and frequencies.

Today, fan manufacturers use in-house software to determine the correct fan size and specification in relation to an application; whether the fan’s to be used within a piece of equipment as a purge fan to remove gas build up or as a standalone top drive drilling cooler solution. This software will determine the required air volume and the pressure needed proportional to the aperture – such as in a ducted system – enabling optimisation of fan performance.

If the duty point, or the required flow or air velocity through which the air has to pass and the space within which the fans needs to be housed is already known, the ideal size of fan for the role can be selected.

How does the custom fan design process work?

Once the specification has been agreed, the fan manufacturer will use an array of design software, such as 3D modelling, drawings, basic rendering and animations to bring the fan design to life.

This should take account of physical space restraints and the material preference, be that mild steel, stainless steel or other, as well as required protection such as powder coating, specialist paint finish or PTFE coating to protect the fan casing from corrosion.

Ensuring that the fan manufacturer is aware of the environment in which the fan has to operate is important too, such as whether it needs to be ATEX explosion-proof, anti-sparking or IECEx flameproof. This is particularly relevant to the oil & gas sector and should include positive material identification (PMI) testing to ensure that the fan is capable of operating in the specific environment safely and effectively.

Other things to take account of are frequency, voltage or special motor requirements for use in different global markets. In the oil sector, where top drives are concerned, fans have to be rated to the right specification so that they can direct ambient cool air to prevent motor overheating during drilling.

Next, other factors such as inlet and discharge options – whether open or connected – need to be considered. Be sure that the fan manufacturer ascertains if your fan requires a mounting flange, inlet filter, spigot, dampers, guards, flexible connections or an AV mount connected to the motor or the inlet to remove vibration from fan to the system. Where drilling is concerned, a top drive fan solution will also need to remove dust and other contaminants, so that operations and drilling cycles are not impacted by foreign material entering the drilling housing.

The fan manufacturer should also assess whether a mounting pedestal, brackets, or feet on the motor in relation to the fan is required.

It should also establish if the fan and motor need to be incorporated onto a skid, which can be wired and positioned ready for the customer to fit ancillaries. Other factors that should be on the checklist include the requirements in terms of cables, wiring harnesses and electrical plugs as well as enclosures, be that standard or custom-built – often the case in the oil & gas sector.

With all these boxes ticked, the fan manufacturing partner should be able to present the options, variants and the pros and cons of each, taking into account any additional factors that you might identify. With all that done, the manufacturer should be able to provide an accurate quote in terms of pricing and manufacture timeframes.

Real-life custom fan testing process

Once the manufacturing partner and preferred design are chosen, the next step to bringing a custom fan to reality is the development of a prototype to provide absolute certainty that the fan meets all expectations.

This should be tested to measure airflow, pressure and current. The fan manufacturer should also provide a performance curve to demonstrate the fan’s capabilities, examining performance, vibration, noise, speed, and a heat run for three hours to measure resistance across the windings from cold to hot; this ensures that the loading on the motor is correct. From here, any final changes can be made based on sizing and performance before the prototype is sent for trialling in situ.

What else should you look for in a custom fan manufacturer?

As with any good manufacturer, it’s worth checking that your fan partner has both ISO 9001:2015 quality management system and ISO 14001:2015 in place. That, alongside a full performance guarantee and the CE Mark, should offer certainty of quality and customer satisfaction.

Following these guidelines means that the correct manufacturing partner can be found and that there’s a simple step-by-step road map to the creation of a custom fan solution designed to save money over off-the-shelf alternatives and provide your business with a product that is smaller, more efficient, faster or cheaper.

Top drivers case study

ACI has worked with OEMs specialising in the oil & gas sector, providing solutions to offshore oil & gas drilling fields the world over, including the Gulf of Mexico. Its fans are developed for specific tasks, among which is the cooling of drilling units in harsh environments, specifically to extend drilling windows during operations, increasing performance in operations such as directional or horizontal drilling, at the same time as enhancing safety.

Top drive motors rotate the drill string during the drilling process and are suspended from the derrick, or the mast, of the rig. Often outputting in excess of 1,000kW, these power swivels turn the shaft to which the drill string is screwed and can become subject to overheating.

Preventing overheating of top drive motors during drilling is critical, as is the prevention of downtime caused by debris that has the potential to clog the top-driver drill housing, suspending operations or slowing productivity.

To address this issue ACI has developed a series of integrated air-cooling solutions that are housed within top drivers to effectively cool drilling units. Using a clean air blower, the centrifugal units are designed to self-clean without the need for additional filters. This is vital for the sector as downtime, caused through unplanned maintenance, can dramatically reduce productivity.

ACI’s high-capacity cooling blowers have been created to endure the harshest of environments even under extreme conditions. The cooling blowers not only prevent overheating, but force out any debris such as dirt particles, insects, snow, and water, before it enters the cooling air stream, helping to keep operations on schedule.

Matt Shelley is with Air Control Industries