Technical Talk with Frank Ferguson - DSH Systems
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Technical Talk with Frank Ferguson

In our new feature, DSH’s Head engineer Frank answers some of the more common questions we receive regarding our hoppers.  

First, some background information on Frank!

Frank has a degree in mechanical engineering and a background in material handling systems. He has been with DSH Systems for 10 years and is absolutely integral to the team. He completes technical assessments, calculations and drawings on all components relating to DSH hoppers, as well as offering advice and recommendations on our systems. He has a sharp, practical mind and an eye for precision, and so is our go to in the office for anything even remotely engineering based (whether that be a difficult math’s equation or explaining the finer points of how our hoppers operate). If you have a question for Frank or would like your queries to be featured in our next Technical Talk post – get in touch!

And now, on to Frank.

How do I start the order process for a DSH System, and what do I need to provide?

At the start of every customer enquiry, we request the completion of a questionnaire form that requests all the pertinent information required to correctly assess if a DSH system is suitable for customer needs. If so, we use this information to determine what size and hopper configuration would be most suitable.

There are approximately 20 important pieces of information that DSH utilizes to calculate which hopper size and configuration will work best, but the most vital pieces of information are product type, flowrate and bulk density.

What products will work through a DSH hopper system?

DSH hoppers work well with a wide range of dry, granular, free flowing products, but generally not with fine powder, sticky, fibrous or very lumpy products. We have tested and installed hoppers for use with various grains such as wheat or barley, fertilizers, minerals, or quarry products, as well as many others. (To see a list of tested products, click here)

What is a flowrate?

Flowrate is the mass or weight of product per hour that the hopper can transfer. It can be expressed in:

Tonnes per hour (1 tonne = 1000 kg)

British Tons per hour (1 British ton = 2240 lbs)

US Short Tons per hour (1 US Short ton = 2000 lbs)

Bushels per hour (grain) (1 Bushel = 1.244 ft³ or 0.0352 m³)

In New Zealand (where DSH Systems Ltd is based) we use the metric system; however, we are able to converse and convert into any unit used in other countries.

How do you Calculate a flowrate?

There are two ways to determine system flowrate.

The first is referring to the conveyor or valve manufacturers specifications OR the plant or equipment records (note that most conveying systems do not run at the manufacturers maximum design capacity, but at a lower capacity)

The second (and preferred) method is to physically measure the flowrate, where possible. To calculate this, divide the time it takes to fill a truck/silo etc. in hours by the net product weight (tonnes or tons). Remember to only include the time that the product is continuously flowing and deduct any time periods in which the product is not flowing.

Why is determining the flowrate so important?

DSH Hoppers perform best and minimise dust emissions when operating at a consistent flowrate in the range of 80-100% of design capacity. An accurate flow rate means the hopper will be correctly sized, operate correctly from day one and functions at its optimal rate, thus reducing dust more efficiently.

What do you mean when you refer to bulk density?

Bulk density is the mass or weight of the product per litre, cubic meter, or cubic foot. When we refer to bulk density, we are interested in the loose bulk density, i.e., when the product is poured into a pile on the floor or into a container, without any consolidation, compaction, or vibration, as this best reflects the state of the product as it passes through a DSH hopper.

What can impact my bulk density measurements?

Product bulk density can be affected by moisture and oil (grains) content of the product itself and there can often be variations from one application to another even when handling the same product. As it can vary significantly, it is important to verify your bulk density by measurement on site, where possible.

How do I measure the bulk density?

Our preferred way to measure bulk density is the following.

  1. Take an empty container of known volume and place it on accurate scales of suitable rating.
  2. With the container on the scales, tare to zero.
  3. Pour the product into the container until it is flat and level with the top (or a volume mark). Do not compress or compact the product.
  4. Record the net weight of the product.
  5. Divide the product net weight by the product volume to give grams or kilograms / litre (convert units if necessary).


Why do you need all this information?

We use the flowrate and bulk density of products to calculate the size of the hopper and the size and number of springs required, to ensure that we provide the best system for your application.

The hoppers’ ability to reduce dust is only as good as the information we receive, so it is important to be as accurate as possible. We are always available to discuss any questions you might have in calculating the above, as we want to make sure that we are providing the best system for the job.


I hope this helps to enlighten you as to the critical information that we require and its impact on the final results.

If you have a question you would like answered please get in contact via the contact form on our website.

Until next time,

Frank Ferguson

Want to know more about our product range? Click here!

Interested in installing your own DSH System? Find your nearest distributor here



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