Leaking shafts

Are you…

• Spending valuable time maintaining shaft seals on your rotary valves?
• Spending money on raw materials that end up on the floor?
• Wasting time and money processing materials that don’t reach the end of the process?
• Struggling to maintain housekeeping & health & safety standards?
• Looking for significant productivity improvements?

Leaking rotary shaft seals are an ‘age old’ problem that Engineers have been facing for many many years and even though there are a number of established solutions to this issue, some are more cost effective than others.

If your rotary valves look similar to the one shown in the video then there are a number facts that can instantly be drawn about your production process.

• Raw material spend will be higher than it needs to be
• Your production capacity will be lower than it could be
• Your housekeeping and health and safety standards will be lower than they could be
• More and more time will be spent maintaining shafts at the detriment of your improvement projects
• Materials that never reach the end of your process as a finished product will be unnecessarily wearing out your equipment
• Your overall productivity will be much lower than it could be meaning that your cost per unit of product manufactured will be higher than it needs to be

In most industries, maintaining competitiveness isn’t an option – it’s a requirement, and during tough economic times this requirement becomes a necessity if we want to survive. We all seem to be searching for efficiency improvements to maintain profit margins and when we find plausible opportunities we then struggle to find the time to investigate and implement solutions. Some production issues can absorb more man hours than others and dealing with these issues first can free up more time to allocate to other efficiency projects.

Established Solution – Gland Packing

Using gland packing to seal your leaking rotary valve is an established temporary solution to leaking shafts but without a doubt will drain more of your engineering resources than any other. Tightening or replacing the packing in the seal will improve things for a short period of time but this activity will turn out to be highly repetitive and largely ineffective in eliminating the issue. How much more time would your Maintenance Team be able to invest in improvement projects if they never had to touch another gland seal again!

Established Solution – Air Purging

Air purging of shaft seals is another method commonly used to cure rotating shaft leakage where air is purged at a slightly elevated pressure to that of the conveying air and is forced into the shaft seal externally to ‘balance’ the leak. Although in many cases this can be quite an effective solution it can be ‘hit and miss’ as to whether it will work reliably. If you also factor in the cost of generating compressed air which is typically anywhere between £0.01 and £0.03 per cubic metre of air used and then in addition to this factor in the increase in compressed air usage as wear increases in the seal then this becomes an expensive solution to the problem. Now, instead of spending unnecessarily on leaked raw materials you’re now spending on compressed air and what happens if your compressor breaks down!

MID’s Mechanical Seals

MID have been offering mechanical seals as an option on all of our rotary valves for the last 25 years and as far as we’re aware, they offer the most cost effective and reliable solution to the problem of leaking shafts.

Two Nihard rings are ground with a slight chamfer and the edges are then lapped together forming the seal. Fitted to the valve shaft during manufacture, their mating faces are so smooth that they squeeze out all of the air inbetween them and ‘stick’ together. Two elastomeric ‘O’ rings are then used to provide just the right force on the mating faces to maintain the seal integrity. By using the most appropriate elastomer, our mechanical seals can be used up to 300 degrees Celsius.

Costing no more than a few hundred pounds, the payback on our seals can be as short as a few days and considering that valves from MID are “Engineered to Last” the benefits will run on and on long into the future.

If you suffer from leaking rotary valves then purchasing your valve with mechanical seals from MID will provide the following instant benefits;

• Complete elimination of material leaking from your shaft
• Complete elimination of shaft maintenance activities allowing you to invest time in other areas of the plant
• Instant improvement in housekeeping and health and safety standards
• Decrease in raw material usage
• Increase in your production capacity
• Decrease in cost per unit of product manufactured

If you need more information on our mechanical seals, their application and benefits then please feel free to contact the office to speak to a member of the team.

Cartridge Seals

Due to the success in using mechanical seals in our rotary valves, we can also supply them in cartridge form for fitment to screw conveyors. Please see here for more details on this.