RAREL - Machines for the Lab

Frequency Asked Questions - Laboratory



A Few FAQs ~ Laboratory

Q: How long should it take to build a RAREL Rules high shear mixer?

high shear domestic socket A: Our Nick Preece currently holds the record at 19 minutes exactly, including gasket work. But Nick has assembled and dis-assembled our high shear mixers many times. As you will read in the Builder Owner Manual, you should not hurry your first build. You should instead concentrate on understanding the components and making the Builder Owner Manual your own. Enjoy taking evenings out to think about the mixer and keep reading the manual. If you absolutely MUST hurry, then do not attempt a first build in less than 4 days. If you build in anything less, then you may not have read and re-read the Bowman sufficiently.

Q: Do you sell to China and India?

A: RAREL sells its books throughout the world. It is not possible for us to speak for the various suppliers of RAREL Rules components. You must contact each component supplier to find out their individual terms and conditions, and whether the components they can offer are suitable in your country. At the time of writing, all our suppliers ship to Europe, Australasia and South America.

Q: How viscous can my target mixture be, before my RAREL Rules homogeniser fails to circulate properly?

A: You can only know by testing, either at your facility or at ours. The higher the target volume, the lower the permissable viscosity. Viscosity also often reduces as temperature rises, though viscosity can also be affected by thixatropic behaviour. The higher the rpm, the better the mixing characteristics, in a simple world. Unfortunately, we do not live in a simple world. This is one of the reasons why our machines cannot be used without a speed controller.

Your application may work well with a RAREL Rules machine at 800rpm. However, far from being twice as good at 1600rpm, it may not work at all at such speeds.

Q: There is a rubber ring called the Spacer Washer fitted over the Hydraulic RAM. What is it for?

A: It has three purposes. (a) It is a cushion to prevent damage to the RAREL High Performance food grade bearing during assembly. This can happen if the Puller Installer Tool is not used during assembly, or is used incorrectly. (b) It damps vibrations. (c) It acts as a back-up oil seal in side entry applications. It provides partial containment of leakages, if the Viton oil seal is failing or has failed.

Q: Why do some of your components have such strange names?

A: When Necessity Green was in the early months of high shear development, she purchased stainless steel components from wherever she could find products similar to what she needed. She then re-machined as required, into parts for her embryonic high shear mixer. Even though we can now make most of these components from stock steel, Nessy's original descriptions remain on our CAD drawings.

Q: One of your competitors claims higher shear for the same electric motor power. Why is your product inferior?

A: It is not in our competitors' best interests to compare like with like. We default to 1400rpm in the interests of longevity and reliability. If your application works at 1400rpm, why go higher?

However, all our components are specified and tested to 2,800rpm and when they eventually wear out, you can cost effectively replace them yourself.

The speed controller actually allows you to run the motor so fast, that the motor quickly self-destructs. Don't do it! The speed contoller electronically monitors and logs all such excesses.

We think we know which competitor you are referring to. We are flattered by their dirty tricks. For their own reasons, they routinely neglect to compare their products with RAREL on price, quality, reliability, robustness, versatility, low speed shear, high temperature performance and cost of ownership.

Q: One of your competitors has written me a letter, which asserts that RAREL offers no guarantees on its products. Is this true?

A: No. our products are books called Builder Owner Manuals or Bowmans. If our Bowmans are delivered to you damaged in transit, unreadable, or badly manufactured, then they will be replaced. If the Bowmans are proven to contain disingenuous information, or false claims, they will be replaced with a corrected version.

We would be interested to receive a photocopy of the letter you received, for publication on this website.

After you have read your Bowman, you may decide to approach the various suppliers named elsewhere on this website, with a view to building your own high shear mixer. Each of these has its own guarantees and each is responsible for its own conduct.

RAREL's guarantee document will be made available on application. Prospective Builder Owners must approach each of the component suppliers for their terms and conditions. RAREL does not undertake to control, influence or assure the conduct of any company besides RAREL, but will act swiftly to de-select suppliers, if they fail to meet the standards required by the law and by RAREL.

Q: You talk of side entry and top entry mounting for your high shear mixers. Can I mount mine beneath my mixing tank?

A: No. Our mixer is fitted with a Viton oil seal, followed by a back-up 'O' ring, which should not be relied on for any length of time. For a bottom entry architecture, you would need an extra seal to guarantee that nothing dripped onto your electric motor and its wiring.

The versatility of the RAREL design allows you to fit your own extra seal, if you must have bottom entry architecture. In fact, the RAREL design allows Builder Owners to make all sorts of bespoke modifications and improvements and these enhancements are limited only by a Builder Owner's imagination.

However, RAREL cannot offer technical support for such off-shoots. Instead, we put people with ideas in touch with people who have already turned those ideas into a customised accessory. Additionally, we offer to publicise the products of accessory providers, free of charge, on this website.

Q: My lab has in the past purchased several machines marketed to us as "Laboratory High Shear Mixers". Without exception, these have been bench mounted machines with a capacity of 1 - 5 litres. Why are you marketing your machine as a lab mixer, when it starts at 25 litres and is floor standing?

A: Our machine plugs into a single phase socket and can be bench mounted if a ceiling mounted hoist can be provided, to raise it and lower it.

However, it weighs nearly 50 kilos, so our bias towards Builder Owner Safety, leads us to discourage bench mounting.

Many (but not all) laboratories need RAREL Rules capacity when they have to make up large batches of reagents or mixtures to a very high standard of dispersion and repeatability. Examples might be sugar solutions and agars for stock, but which must also yield entirely repeatable and dependable results.

Furthermore, laboratories often need to manage pilot plants. Unfortunately, many technicians and scientists have to commute to a distant shop floor for such pilots, where 3 phase electricity is readily available. RAREL Rules mean that pilots can often be run within the lab, particularly those labs with no ready access to 3 phase electricity.

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