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So you are thinking about buying an industrial centrifuge but don’t know where to start? You have done your research, but there are still some lingering doubts and questions. Industrial centrifuges are considered capital equipment and therefore need careful consideration.
We leverage our 40 years of experience in the industrial centrifuge business to help potential buyers make the right decision. Here we have narrowed the centrifuge selection process down into 9 steps to picking the right industrial centrifuge.
As a bonus, we have summarized a set of questions to ask your potential supplier!
by Sanjay Prabhu MSME
Engineering Manager, Dolphin Centrifuge
As they say, ‘Defining a problem is half the solution.’ Having a clear understanding of your separation needs and expected results is essential. To define your separation needs, you first need to understand the type of fluid and the type and amount of contaminants.
This necessary information is critical for us to understand your requirements and offer the right centrifuge.
In this initial stage, you have probably considered various separation technologies such as settling, filtration, hydro-cyclones, filter-presses, screw presses, and other similar separation equipment. These technologies have a specific niche in the field, but few apply to a wide range of applications.
Having a good understanding of your specific requirements helps narrow down the available options.
If you have already eliminated media-based separation (filters, presses, membranes, etc.) from your possible solutions, either a low or a high centrifugal force centrifuge may be appropriate.
If low g-force (< 1000 Gs of centrifugal force) centrifuges are not feasible due to particle size and fluid properties, higher speed and higher centrifugal force centrifuges may be worth considering.
Furthermore, many high g-force alternatives are appropriate for various applications. We have written a detailed article about the difference between decanter centrifuges and disc centrifuges. That article will help you narrow down the choice between decanter and high-speed disc centrifuges.
Another often ignored resource in the selection process is industry contacts. It is easy to reach out to colleagues or contacts within your industry to get recommendations on centrifuge types. In addition to referrals, you might even get to know the pitfalls and indirect advantages of various industrial centrifuges.
A centrifuge supplier can also be an excellent resource for identifying the right centrifuge for your application. Of course, you must know a supplier's natural bias and ensure that the selection satisfies the process requirements, standard vs. auxiliary equipment, financial considerations, vendor experience/expertise, and technical support/customer service.
We discuss the selection criteria for your centrifuge suppliers in a later section.
As with all industrial equipment, centrifuges come in various sizes or capacities. Industrial centrifuge throughput capacities quite often confuse and mislead customers.
In other words, process capacity is the actual throughput a user can expect for their process fluid. Maximum capacity, also known as swallowing or hydraulic capacity, is the maximum flow rate the centrifuge can handle with water.
It is not uncommon for different vendors to quote vastly different capacities for the same centrifuge model. There are a few reasons for this anomaly.
First, the seller may not have a large centrifuge to handle your requirement. In that case, the ‘swallowing’ capacity (i.e., the hydraulic capacity) is misrepresented as the centrifuge’s process capacity.
Second, if the buyer is on a tight budget, the seller may try to sell a smaller capacity centrifuge by overstating the maximum capacity as potential process capacity.
Third, the seller does not possess the knowledge/experience to understand the buyer’s application. In this case, the seller may mention the OEM published capacity (max. Swallowing ability) as the processing capacity.
It is important to note that a specific centrifuge’s processing capacity depends on multiple factors, including:
Based on the above, it is more important to understand how the centrifuge capacities are rated. It is equally important to ask the potential supplier to estimate the process flow rate for your fluid mix. If in doubt, the buyer may warrant additional research and search for a more informed supplier.
Auxillary equipment integral to centrifuge systems is also known as options. The main reason for adding options is to augment the working of the centrifuge to get maximum efficiency from the centrifuge.
Typical centrifuge options include pumps, sludge collection receptacles, in-line heaters, pre and post-filters, clean fluid collection and pumping systems, and other accessories.
It is important to note that what some suppliers consider standard (included) accessories, other suppliers may consider optional equipment.
For example, a control system, water harness (for sludge ejection controls), base platform (skid), gauges, instruments, and sensors, are standard accessories supplied with all centrifuges sold by Dolphin Centrifuge.
Some suppliers may consider these accessories as chargeable options. In other words, their scope of supply for a given price point may include a bare centrifuge with a motor. Therefore it is essential to make an ‘apples-to-apples comparison between different sellers’ scope of supply.
Depending on the application, there are specific options that we encourage our buyers to consider. For example, if a customer intends to process thick, used oil, we would strongly suggest an optional heater because lower viscosity (higher temperature) is key to efficient centrifugation of thick oils.
One of the most common complaints we hear from our customers is the lack of adequate heating capacity! It is much easier and cheaper to add a heating system during the centrifuge build process than to add one post-installation. Therefore we encourage our customers to err on the side of extra heat capacity.
Another example that illustrates the need for some optional equipment follows. Many centrifuges discharge the separated sludge through the bottom of the centrifuge frame. Customers may choose to install these centrifuges on elevated platforms to allow for sludge collection underneath.
However, adding the optional skid integrated sludge collection and disposal system allows the skid to be flexible, i.e., mobile. It also eliminates the need for the customer to build a permanent platform.
In summary, we suggest evaluating and choosing the right options for your particular application from the start. The right choices can make the difference between average centrifuge performance and excellent centrifuge performance.
Every buyer would like a new centrifuge if it was not for budgetary or time constraints. For this discussion, we are discussing only centrifuges from established, brand-name manufacturers like Alfa Laval. We look at this consideration from 4 different aspects.
A remanufactured centrifuge can save a buyer up to 50% compared to a new centrifuge. This cost savings is highly subjective and depends on the type, make, and centrifuge model.
Lead-time also plays a vital role in this decision of new versus remanufactured. Typical lead times for new centrifuge systems can be 8 to 18 months compared to those for remanufactured centrifuge systems, around 2 to 5 months.
Accessories (heaters, pumps, sludge systems, and filters) are important considerations for choosing between new and remanufactured centrifuges. New centrifuges from OEM generally come with proprietary accessories. This factor is important because the buyer depends on the OEM for these accessories’ parts and services.
For example, control systems from centrifuge OEMs are proprietary for their particular centrifuges. The control system program cannot be accessed or modified by the user. The OEMs cannot change the programs or control systems to suit buyers' needs.
The OEMs’ inability to customize is understandable, given many OEM systems, making customization impractical. This fact leads to other restrictions when dealing with new centrifuges from OEMs. The accessories (heaters, pumps, sludge systems) offered with new centrifuges are also proprietary. Parts and services of these additions are also highly dependent on the OEMs.
Non-OEM centrifuge suppliers with thorough knowledge and experience in centrifuges can address this issue. Dolphin Centrifuge is one of the few companies capable of bringing a high customization level to remanufactured centrifuges. We can use state-of-the-art technology to extract maximum performance from remanufactured OEM centrifuges.
In summary, a prospective buyer can see cost and lead-time benefits from choosing the remanufactured centrifuge option. Accessories and the ability to customize systems for unique applications also play a role in the final decision.
This section discusses another option available to centrifuge buyers, which is new, generic centrifuges. New, generic centrifuges refer to copies of brand-name centrifuges produced by third parties. The bulk of these centrifuges are manufactured in China and sold under various brands worldwide.
The primary reason for considering these generic centrifuges is their price point compared to new, reputed-brand centrifuges. However, the equation changes when comparing these generic centrifuges to remanufactured reputed-brand (like Alfa Laval) centrifuges.
In other words, a customer can source an Alfa Laval centrifuge, which is remanufactured in the US at a similar price point to a new, generic centrifuge. At the same price level, the advantages of the remanufactured, branded centrifuge are apparent.
Some of these advantages are listed below.
Reputed brand centrifuges such as Alfa Laval have more than 100 years of manufacturing experience. They are well known for their material quality and robust design. These branded centrifuges are commonly known to last over 50 years. Generic centrifuge manufacturers cannot easily make such claims.
R&D is a significant part of all branded centrifuge manufacturing operations. R&D allows manufacturers like Alfa Laval to incorporate the latest learnings and technologies into their evolving centrifuges.
Generic centrifuge manufacturers do not typically have any R&D but rely on their low price point as the primary selling feature.
Branded centrifuges have been around long enough to create their spare parts ecosystem. Consequently, genuine and aftermarket parts for branded centrifuges are readily available worldwide.
Generic manufacturers use parts specific to only their centrifuges. Getting spare parts for these centrifuges can not be assured.
With thousands of units in operation worldwide, branded centrifuges are familiar to centrifuge technicians worldwide. Therefore servicing of branded centrifuges is readily available in most locations.
Generic centrifuge copies are not as widely prevalent as their branded counterparts. Experienced service technicians can be hard or impossible to find outside of the manufacturer’s technicians.
Remanufactured is a loosely used term, the scope of which is dependent on the remanufacturer. A remanufactured centrifuge from a used equipment dealer could mean a paint coat on a barely functional centrifuge compared to a complete, ‘rebuilt from scratch centrifuge’ from a reputed centrifuge company.
Some of the other factors to consider in a remanufactured centrifuge are the centrifuge’s prior use and present location. Following is an explanation of each of these factors.
Prior use of the centrifuge refers to the previous application of the centrifuge in its earlier life. For example, a centrifuge from a highly abrasive application like sand or drilling mud needs careful inspection before consideration. It is not easy to revive centrifuge bowl components with excessive wear. A worn-out bowl limits the useful life of the centrifuge.
The present location of the centrifuge under consideration is essential if the centrifuge is in a distant geographical area from the seller. In such cases, it is difficult for the seller to perform a thorough inspection of the centrifuge before buying.
Ideally, the seller should have the centrifuge on offer physically inspected and available for the prospective buyer’s inspection before purchase.
OEMs, specialized centrifuge companies, and centrifuge traders all sell ‘remanufactured’ centrifuges. Selecting the right supplier is one of the most critical choices facing a potential buyer – whom should you buy from?
We will break down this selection step into factors worth considering while choosing the right supplier for your industrial centrifuge.
A branded OEM is an established company. For example, Alfa Laval, the gold standard in centrifuges, has been around for over 100 years. They should be the first choice for any buyer looking for a remanufactured centrifuge. However, as noted in section 5, this is often not feasible due to cost concerns.
Finally, super-specialized centrifuge companies specialize in certain types of centrifuges and cater only to that specific market. Dolphin Centrifuge is one such company that specializes in decanter and disc centrifuges. Within that sub-category, we specialize in Alfa Laval branded centrifuges.
Generalized centrifuge companies sell all different types and brands of remanufactured centrifuges. Some of these companies have been in business for over 25 years. There are a few different types of companies within this category.
Centrifuge traders buy and sell all varieties of industrial centrifuges, from basket centrifuges to pusher centrifuges to decanter and disc centrifuges. Then, centrifuge repair companies specialize in repairing and ultimately selling used centrifuges of different types.
The application experience is a critical differentiating factor worth considering. As discussed in the previous point, generalized centrifuge traders cater to all markets and applications. They offer a wide selection; however, they may lack in-depth application experience. These traders tend to be more generalized and could be a good source for buyers with in-house centrifuge expertise.
On the other hand, OEMs have various divisions within their company, each with in-depth application experience catering to specific sectors.
Centrifuge suppliers specializing in specific types of centrifuges tend to have in-depth application experience. This fact is especially true for specialized centrifuge suppliers. They are established and have been in the business long enough to have experience with practically all applications of their specific machines.
Centrifuge supplier’s owned inventory refers to the stock of centrifuges owned by the potential supplier. This owned inventory is an essential consideration for potential buyers for the reasons explained below.
The main component of the centrifuge is the rotating bowl, which is the heart of the centrifuge. While frame and transmission parts can be repaired or replaced, the centrifuge bowl is not recoverable from excessive wear.
Some established centrifuge suppliers buy and stock gently used centrifuges whenever and wherever they are available. This inventory of pre-selected centrifuges offers the supplier the advantage of providing centrifuges with minimal wear bowls.
OEMs have a similar advantage of having a stock of gently used centrifuges, which they receive as trade-ins.
Suppliers who don’t have their stock of pre-selected centrifuges often seek used centrifuges once they have a buyer's purchase commitment. At this point, it is not always possible to find centrifuges having bowls without significant wear. There is also the likelihood of procuring the least cost centrifuge at this point in the transaction.
In summary, it is worth inquiring about the ownership of the proposed centrifuge for the reasons above.
A remanufactured centrifuge system involves certain sub-activities that are critical to the long-term trouble-free operation of the centrifuge.
These activities cover the following main areas:
OEMs have specific remanufactured centrifuge divisions which integrate all of the above under one roof. The result is a fully integrated centrifuge system with an assured durable operation.
Few specialized centrifuge suppliers can perform all of these activities in-house. Dolphin Centrifuge is one such dedicated centrifuge supplier.
Generalized centrifuge traders cannot have all these facilities in-house because of their broad scope of supply. Therefore, it is not uncommon to see the centrifuge seller, the remanufacturer, the controls builder, and the system integrator being separate, independent companies or individuals. The expertise and knowledge are lost if there isn’t single entity ownership or diverged focus.
The advantage of this process is the potential time savings from leveraged independent resources. However, there is no single point of contact or knowledgeable source for support in post-sales issues or technical support.
There is no corporate memory to implement the ” lessons learned” into future centrifuge systems under these circumstances. These learnings relate to inter-component issues, such as specific control features modified based on certain centrifuge features particular to the application.
Finally, the system build location becomes critical if imported subsystems are involved. The system's origin is crucial due to the difference between North American and European/Asian engineering standards.
For example, control panel components, motors, fasteners, and other components adhere to different standards depending on the location. These differences can be a significant issue when users cannot find a simple fastener or electrical component anywhere in the local market.
As mentioned in section 6 above, spare parts availability is one of the advantages of choosing a branded centrifuge OEM. However, specialized centrifuge suppliers can also afford to carry a large spare parts inventory. The availability of spare parts is due to their narrow focus on specific centrifuges.
On the other hand, generalized centrifuge traders cannot carry all the spare parts for the different brands and types of centrifuges. Of course, there are other sources of generic spare parts for branded centrifuges. But then the buyer has to find and source spare parts independently.
Spare parts are not always ‘spare’! Often the centrifuge operator is looking for parts when there is a breakdown. At this point is a time-sensitive situation, and a centrifuge supplier who also carries parts for the centrifuges they sell is beneficial.
Spare assemblies refer primarily to bowl assemblies. It is easier to find used bowl assemblies for branded centrifuges, which are prevalent in the market.
A specialized centrifuge supplier with a stock of centrifuges is your first choice for spare centrifuge bowl assemblies. They can offer sound, reusable bowl assemblies from their pre-selected stock. This availability also applies to frame assemblies and other large, expensive parts.
OEMs offer a sample testing service wherein they process a small sample of the potential customers’ fluid through a pilot-scale, high-speed centrifuge to evaluate centrifuges’ applicability.
Few other centrifuge suppliers offer this service. But it is recommended since it can provide additional assurance of centrifuge applicability to the customer.
Some specialized centrifuge suppliers can process a customer sample and provide a detailed test report. Based on their experience, they can also make centrifuge recommendations depending on the rest results.
The ability to test your sample is a question worth asking all your potential centrifuge suppliers.
A warranty is only as good as the company behind the warranty. One important consideration with a centrifuge warranty is that it is a mechanical warranty.
Given that a centrifuge is a mechanical separation device, it is impossible to provide a process warranty. This inability to provide a process warranty is because different fluid properties, operating conditions, and machine settings will produce differing results. Therefore there is no way to predict and guarantee process results.
This final step will discuss the importance of some post-purchase factors that the buyer should consider before making the final purchase decision. We have divided this section into three important after-sales factors.
The factory acceptance test is an opportunity for the buyer to visit the supplier’s factory and witness the final testing of the centrifuge they purchased. FAT is an excellent opportunity for the buyer to inspect and see their centrifuge system operating.
FAT is routinely offered by OEMs, especially when their customers have the FAT as part of the buying process.
Specialized centrifuge companies, such as Dolphin Centrifuge, offer FAT and see it as an opportunity to familiarize their customers with the centrifuge. It is also a chance for the customer’s operators to get some hands-on experience on the equipment under the supplier’s guidance.
Some generalized centrifuge traders may offer FAT if specifically requested. It will depend upon the system integrator's actual testing location and availability, who may not be the seller.
Centrifuges are durable machines, but they are not filters! In other words, they are machines, and machinery needs to be maintained to ensure reliable operation. Also, centrifuges are not familiar machines.
As a result, after-sales technical support is all the more critical for centrifuges. In-depth centrifuge knowledge and experience are required to offer technical support.
Specialized centrifuge suppliers are well equipped to provide reliable technical support and maintenance. Their ability to offer tech support is due to their narrow focus on the centrifuges they specialize in. Their dedicated focus gives them a deep understanding of centrifuge products and helps in unique situations.
It is worth mentioning here that Dolphin Centrifuge offers lifetime technical support to all our customers.
As mentioned above, under the FAT section, customers can send their operators to the supplier during the FAT to get initial training. OEMs and certain specialized centrifuge manufacturers offer FAT. One can consider FAT as factory training.
Though the OEMs typically charge for FAT, specialized centrifuge suppliers (such as Dolphin Centrifuge) include this service without an additional charge.
Both OEMs and specialized centrifuge remanufacturers offer on-site training. This training helps the customer fine-tune the centrifuge on their actual process fluid on continuous flow. The customer’s operators can understand the centrifuge, control system, and servicing procedures.
Most generalized centrifuge traders offer on-site training as well. But again, depending on the centrifuge trader, a generic centrifuge technician may not have the in-depth knowledge to answer all questions. This lack of knowledge is especially the case if the technician is unfamiliar with the centrifuge and the controls are from a 3rd party.
Selecting the correct centrifuge for your needs is a significant decision. It would be best to consider many factors to choose a centrifuge that works efficiently; it can be easily serviced and at an appropriate price point.
We can summarize the steps mentioned earlier in the form of questions that a prospective centrifuge buyer should ask as they go about selecting a centrifuge and vendor. The answers to these questions will give the customer enough information to make an informed buying decision.
What are the properties of your process fluid?
Is this Liquid/ Liquid or Liquid/ Solid or Liquid/ Liquid/ Solid separation?
What is your capacity requirement? How many gallons per minute?
What is the % of each phase in your process fluid?
Which phase(s) are you trying to recover? (i.e., Valuable Phase)
Do you need equipment for hazardous areas, or Explosion Proof classified?
What data do you need from us to recommend a centrifuge for our application?
What are the rated capacity and expected process capacity on the process fluid of the centrifuge you are offering?
How should we pre-treat our process fluid to get the maximum out of the centrifuge?
What accessories do you include with the centrifuge?
Do you recommend we include any additional options? If so, why?
Can you offer the same or similar centrifuge as a new one? If so, what is the price and delivery time difference?
Who is the original manufacturer of the centrifuge offered? Where was it manufactured, and is the manufacturer still operational?
Are spare parts readily available for this centrifuge? If so, can you refer us to a local (US-based) source?
What was this centrifuge used for in its prior use?
Where is this centrifuge presently located? Is it available for inspection before we decide to buy it?
How long have you been in business?
Can you share a portfolio of centrifuges you have supplied?
Have you previously supplied a centrifuge for this application? If so, can you share the details?
Do you currently own the centrifuge you are offering?
Who will remanufacture the centrifuge?
Where will it be remanufactured?
Who will design and build the control system? Where will it be made?
Where will the complete system be integrated, wired, and tested? Will you be present?
Do you carry spare parts for this centrifuge? What about additional bowl assemblies?
Can you test a sample of our process fluid and give us your recommendation?
What kind of warranty do you offer? Can we see your warranty statement?
Can we witness the testing of the centrifuge?
If we need technical assistance with the centrifuge – whom do we call?
If we need technical assistance with the control system – whom do we call?
Can you train our operators at your facility on our centrifuge?
If we need on-site startup assistance, who will provide that support?
We hope this article will help prospective centrifuge buyers to make an informed decision on their centrifuge purchase.
by Sanjay Prabhu MSME
Engineering Manager, Dolphin Centrifuge