In today’s episode of the Dust Safety Science podcast, Ross Blanford, Director of Sales at Masterduct, returns to highlight the top five questions companies have about flexible hoses and ducting.
Three years ago, he appeared in Episode #62 to talk about designing hose systems to handle combustible dust. In today’s episode, he broadens the scope to talk about flexible hose and ducting in general.
The idea for this topic arose from a conversation Ross had with Dr. Chris Cloney regarding their respective Helpdesk operations. If someone has a question related to combustible dust, they can simply reach out to the Dust Safety Science or Dust Safety Academy website and our team will assist them. Similarly, Ross manages a helpdesk for the Masterduct website, where he addresses inquiries about hoses and ducting.
After discussing the questions commonly received, they decided to dedicate a podcast episode to the top five questions about flexible hose and ducting.
Flexible Hose and Ducting Defined
Ross explained that there are several different types of industrial hoses.
“The flexible hoses and ducting that we (Masterduct) manufacture are more on the low pressure side of the industrial hose world. Companies like Continental, Gates and Texel focus on the higher pressure side of the business, but our primary focus is products made from thermoplastic, thermoplastic rubber and also fabrics that carry heated air, cooled air, welding fumes, chemical fumes and many, many different types of abrasive, solid materials. Some examples are flour and sugar in the food industry, powdered pharmaceutical ingredients in that industry, even all the way to powdered milk, grit for roofing tiles, plastic pellets for plastic manufacturers. There are actually 32 different vertical markets where our products are used. So we are one of the more diverse sides of the hose and ducting world.”
Question #1: How Long Will a Hose Last?
Ross pointed out that every application has variables such as different temperatures, pressures, atmospheric conditions, conditions in the area where the hose will be installed and different media going through it.
“We can take all those factors into consideration and choose the hose that will perform the best based on the information that we have. Unless we’ve tested a hose for life expectancy in a particular application and have the data to back that up, it’s really impossible for me to take a hose into a facility and say this hose is going to last nine months and four days. It just doesn’t work that way.”
He added that when PVC hoses near the end of their life expectancy, they tend to start getting stiffer and eventually they’ll even crack and break. If the hoses are made of urethane, the owner primarily has to look for the wear.
“You have to understand that once the Helix wire is exposed, the hose is done and needs to be replaced because it’s no longer safe as well. [Another sign] is if you start seeing cracks around the ends of the hoses where they attach to the machinery or if you start seeing leaks in the hoses.”
Ross said that there’s one dead giveaway that a hose is on its way out – duct tape.
“If you see duct tape on a hose, there’s a 100% chance that it needs to be replaced instead of having more duct tape applied to it.”
Question #2: What Does the Approval Process Look Like?
In the pharmaceutical and food industries, approvals are needed for certain types of hoses.
“On the low pressure side, there’s no approval process to go through,” Ross explained. “People ask me all the time “Are your hoses FDA approved?” And I can say that unlike other types of hoses, there’s no real approval process to go through. We publish in our literature that our hose material complies with an FDA material standard. But ultimately, all that we can say is that our hoses are made from resins on the plastic side or FDA food grade compliant.”
Question #3: Do the Hoses Have Grounding Wire?
“This one kind of drives me nuts a little bit,” Ross laughed. “Because the term grounding wire is used commonly in the hose and ducting world when the actual term that people should be using is “Does your hose have a Helix wire?”
A Helix wire adds stability to the design of the hose and allows it to hold more pressure. In the absence of a helix wire, the only way to accomplish this is to make the hose wall thicker – which is of course less flexible and harder to work with.
“Can the wire be used for grounding?” Ross continued. “Of course it can! But if someone is only relying on the mechanical ground of the grounding wire to a ground connection for safety against arcing and sparking, and if that connection is broken, then there can be a problem. There’s no secondary source of safe transfer for that energy.”
Every day, Ross sees hoses used with combustible dust that shouldn’t be. The only way to effectively protect against a combustible dust or combustible vapour explosion is to have an additive in the plastic or in the fabric that prevents the hose from developing a static charge on the surface up to a particular ohm rating. Hoses rated at or around ten ohms up to the ninth power are considered to be anti-static or static-dissipative.
“For even more protection, we can add carbon black to those hoses, bringing that conductive property up to ten ohms up to the fourth power. So we can actually almost double the effectiveness or the protection that the hose offers. But I’ve been in dozens of plants and seen hoses being used with combustible dust and combustible vapours with no Helix wire at all. This is really common in pharmaceutical plants where they’re trying to keep metal out of the plant for fear of metal contamination, and the same in food processing. In this case, there’s combustible dust going through the hose. There’s no wire at all. How is there supposed to be any sort of grounding? It’s very difficult if not impossible to do.”
A Helix wire is a good secondary protection for hoses handling combustible dust or vapours. Without carbon black or any additive in the plastic or fabric to make the hose static-dissipative or anti-static, one is relying on a mechanical connection that can break in any number of ways.
“The Masterduct urethane products are all food-grade compliant and anti-static, and we’re the only manufacturer in our space that can say that,” Ross said. “With Masterduct, you really don’t have to worry about [things like] ‘Is this hose safe to use?” It’s all safe to use everywhere. And ultimately, as a safety professional, whether it’s food safety or combustible dust safety or operational safety, this is an area that is critically important but often overlooked, and a problem that is very easy to solve.”
Question #4: What is the Difference Between Urethane and PVC in Thermoplastic Hoses?
The primary motivator to buy PVC is that it’s inexpensive. Therefore, Ross gets a lot of questions about why someone should pay more money for a urethane hose when they’re currently using PVC.
“There are three or four different kinds of reasons for that. Urethane is good for a wider range of temperatures. PVC hoses are really only good up to 120°F, where urethane is good for up to 195°F. Urethane is also more abrasion resistant than PVC, offering a much better ROI due to a less frequent replacement. So how many combustible dusts are not abrasive? There are not many.
“Finally, PVC hoses are made with plasticizers, which is an invisible additive that evaporates over time, making the hoses more difficult to work with and stiffer the longer they’re installed. Urethane does not use any plasticizers, so it’s safe to install in any sort of environment. It lasts four to five times longer, and it’s as easy to work with the day you replace it as it is the day that you put it in.”
Question #5: How Much Thought Need to be Put Into Hoses?
“One point that I’d like to reinforce is that when you’re considering equipment in your facility, people pay a lot of attention to the dust collectors, flame preventers or other types of material, but the hoses tend to kind of be an afterthought,” Ross said. “I would encourage people to put as much thought into the hose they select for their dust collector or the pneumatic conveyance system or mist collector or something. Then they do the performance standards of the equipment itself.”
To make sure that the right product is selected for a particular application, the hose and ducting industry uses an acronym that’s spelled ‘Stamped.’
- S stands for size. How long does the hose need to be, and what diameter does the hose need to be?
- T stands for temperature. Is there heat in the area where the hose is going to be installed? Or is the air or air and media going through the hose going to be at any sort of an elevated temperature?
- A stands for atmosphere. What’s in the area? Is it attached to something that’s moving around? Is there something maybe striking the hose? Are there sharp objects in the area? Are there elevated temperatures? Are there low temperatures? What atmospheric conditions could impact the hose performance?
- M stands for media. What’s the hose actually carrying? Is it carrying flour, sugar, concrete, cement, vehicle exhaust, hot air from an oven? What’s going through it?
- P is for pressure. Is there positive or negative pressure on the hose and how much? Positive and negative pressure ratings will be assigned to each hose.
- E stands for end treatments. When the hose is connected to the equipment, is it as simple as using a worm gear clamp or do you need a sanitary moulded-on fitting that doesn’t allow any sort of microbes or any sort of contamination to grow.
- D stands for delivery: Where the hose is needed and when are they needed? How much time is available to find a solution?
Conclusion
“I think we’ve given folks a lot of good things to think about,” Ross said as the interview concluded. “Ultimately, we’re here as a resource as Chris is with the entire Dust Safety Science platform. We certainly appreciate the opportunities to support the organization and to provide, hopefully, some interesting information to your audience.”
If you would like to discuss further, leave your thoughts in the comments section below. You can also reach Ross Blanford directly:
Email: [email protected]
LinkedIn: https://www.linkedin.com/in/rossblanford/
Website: https://www.masterduct.com/
If you have questions about the contents of this or any other podcast episode, you can go to our ‘Questions from the Community’ page and submit a text message or video recording. We will then bring someone on to answer these questions in a future episode.
Resources mentioned
Dust Safety Science
Combustible Dust Incident Database
Dust Safety Science Podcast
Questions from the Community
Dust Safety Academy
Dust Safety Professionals
Dust Safety Share
Companies
Previous Episodes:
DSS062: Designing Hose Systems to Handle Combustible Dust with Ross Blanford
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