Frequently Asked Questions - FAQ
How to make rope ends anti-fray?
Most high temperature and heat resistant plain ropes (those without binders) will fray when cut and then fray more as they are handled. One way to make them not fray is to add a binder - but for some applications the use of a binder is not appropriate (usually due to the lowered temperature limit of the rope or the smoke-off effects when heated.
To make ropes anti-fray as much as possible, there are some other options:
1) Tie a knot and then cut the rope on the "other" side of the knot.
2) Tape the rope at a desired cut location with masking tape, duct tape, aluminum foil tape, silicone self fusing tape or another tape of your choice - then cut the rope half way in the width of the tape. The rope then has a ring of tape at the end as an anti-fray.
3) Slide heat shrink tubing over the rope. Heat the heat shrink - after it has shrunk cut the rope halfway in the width of the heat-shrink tubing.
4) Use two free-end band clamps close together and cut the rope between the clamp locations.
5) Add a dab of some epoxy glue, instant glue, silicone rubber rtv or other suitable adhesive/sealant to the rope and work it into the strands. When the glue is dried, cut the rope with side-cutters in the middle of the glue spot.
6) Spray the rope with hairspray at the area where you want to cut it. When the hairspray sets, cut the rope in the middle of the sprayed area.
7) Cut a short piece of rope from the rope, and un-bundle the yarns. Use one of the yarns as a tie cord around the rope. Cut the rope on the "other" side of the tie-cord location.
8) Use a metallic hog-ring clamped around the rope, and cut the rope on the "other" side of the ring.
These are the best tricks we have learned over the years
How to make sleeve and tubing ends anti-fray?
Most high temperature and heat resistant plain sleeves (those without binders) will fray when cut and then fray more as they are handled. One way to make them not fray is to add a binder - but for some applications the use of a binder is not appropriate (usually due to the lowered temperature limit of the sleeve or the smoke-off effects when heated.
To make sleeves anti-fray as much as possible, there are some other options:
1) Tape the sleeve at a desired cut location with masking tape, duct tape, aluminum foil tape, silicone self fusing tape or another tape of your choice - then cut the sleeve half way in the width of the tape. The sleeve then has a ring of tape at the end as an anti-fray.
2) Slide heat shrink tubing over the sleeve. Heat the heat shrink - after it has shrunk cut the sleeve halfway in the width of the heat-shrink tubing.
3) Use two free-end band clamps close together and cut the sleeve between the clamp locations.
4) Add a dab of some epoxy glue, instant glue, silicone rubber rtv or other suitable adhesive/sealant to the sleeve and work it into the strands. When the glue is dried, cut the sleeve with side-cutters in the middle of the glue application area.
5) Spray the sleeve with hair-spray at the area where you want to cut it. When the hair-spray sets, cut the sleeve in the middle of the sprayed area.
6) Cut a short piece of sleeve from the sleeve, and un-bundle the yarns. Use one of the yarns as a tie cord around the sleeve. Cut the sleeve on the "other" side of the tie-cord location.
7) Use a metallic hog-ring clamped around the sleeve, and cut the sleeve on the "other" side of the ring.
These are the best tricks we have learned over the years.
What smoke emissions from our products may occur when exposed to high temperature?
Many of our products are woven, knitted, needled or coated in machines where some organic lubricating oil is used on the machinery components. A small amount of the oil can remain on the products after production. Some products also use a small amount of organic binder in the manufacturing process. When exposed to high temperature for the first time, these organics can create a small amount of "smoke" until burned-off. This smoking is usually not visible, but may be sensed as a smell.
This smoke-off may take 10 to 15 minutes (at temperatures above 300°F / 149°C) upon the first running of the engine / exhaust system, or heating of the pipe, hose, etc., that has a product installed.
This smoke-off also occurs on products with PSA (pressure-sensitive-adhesive), or with products where an adhesive has been used to laminate layers together. In this case the smoke-off may take longer, as there is usually more adhesive than other materials where the smoke-off is from lubricating oils.
In the case of adhesive smoke-off, we recommend that the area be well ventilated, as the smoke may be from acrylic, silicone or natural rubber adhesive products.
Items that are "heat-cleaned", such as many fabrics and sleeves, have already been heat cycled to remove the organics, and these items do not emit any smoke when heated in situ.
Sometimes smoke may emit from systems where heat-cleaned or oil-free products are used. This may be for example from a piping system where an insulation blanket is installed, and the blanket has been fabricated from organic-free materials; often this is from a coating, cleaner, paint or other item on the pipe itself.
Smoke may emit from removable engine insulation blankets where the blanket is not properly installed, caused by a piece of the outer cold-side fabric being folded or pushed down to contact the hot pipe surface.
What are the common treatments to yarns, fabrics, tapes and sleeves?
When yarns are manufactured, the producer will often apply oils, starches, waxes, or lubricants to the yarns.
These lubricants are necessary to prolong the life of the production machinery, especially for weaving or knitting. Without them many of the precision manufactured parts of the machinery would wear quicker and require costly replacement.
In many cases, untreated tapes, sleeves and fabrics will satisfy all the end use requirements of the customer, however, for some applications further treatment may be necessary. To achieve best performance with some resins, tapes are cleaned using cleaning coupling agents (silanes). On narrow electrical grade tapes, acrylic finishes are applied to the tapes to enhance performance. A summary of treatments available:
How to select insulation sleeve for hose, tube, pipe, wire and cable thermal protection
When a thermal protection sleeve is added to a hose (or wire, cables, tubes or pipes), it adds a thermal time delay to the heat transfer between the hose and the environment it is installed in (assuming there is difference in temperature).
If the assembly (the hose with the protection sleeve) is carrying a hot fluid, then the insulation sleeve helps to keep the assembly from cooling, and the surface temperature of the insulation sleeve will be lower than the surface of the inner hose. This is particularly useful in situations where we are trying to keep hot process fluids from cooling, and also useful in providing burn protection to personnel who may come into casual contact with the assembly if the temperature of the assembly is above the normally accepted 203F safety limit for non-metallic objects.
Generally, the thicker the insulation layer, then the more heat that is kept inside the assembly and the lower the surface temperature of the outside of the insulation will be. That thickness is usually practically effective up to 2" of insulation thickness, after that, adding thickness does not provide much of a benefit but adds cost.
The reverse is also true. If the environment is hot, then the insulation helps to prevent the assembly inside from heating.
Now take into account a situation where a liquid or gas is flowing in the hose, and it is passing through a hotter environment. As the cooler flow goes along the hose, it absorbs heat from the warmer insulation layer. If the flow is very slow, then the heat gain is more than if the flow is faster. So a faster flowing medium in the hose would help by reducing the heat gain.
If there is very low flow (or none in the case of wires and cables) then the hose inside the assembly will eventually reach the same temperature as the environment, but it will take time to do so. In cases where the temperature of the environment cycles, from lets say room temperature to 1000F, then the insulation layer only needs to be thick enough to add a time delay in the heating of the assembly. If the temperature cycle time is short, just a few seconds or perhaps a few minutes, then a thin insulation layer may work. But if the cycle length is long, let's say many hours or days, then eventually the heat will permeate the insulation and be transferred into the hose (or wires, cables).
So the choice of material of the protection sleeve and the thickness of it will play a deciding part of the protection it provides.
If a sleeve material that is good for 1000F exposure is added to a hose, and the sleeve is 1/16" or 1/8" of an inch thick, it will provide a shorter cycle time than if it was 1" or 2" thick. Although the sleeve material may be rated for 1000F, it will not keep the hose inside it cool unless the cycle time is considered and taken into account.
In cases where the environment is very hot continuously, and the flow through the hose is low, then it may require additional cooling mechanisms, such as a cooling liquid line in parallel to the hose, or a flow of air between the hose and the inside of the sleeve.
We have many years of experience in these heat soak applications where hoses, wire and cables are exposed to continuous high environmental temperatures. Please contact us with your details so we can make the correct recommendation of materials and thickness. Details such as hose size (tube or pipe size), flow rates, type of liquid, target temperatures, environment size, type of heat source, flame or molten metal exposure and other parameters are all important considerations.
Tapes are placed in ventilated ovens and the temperatures are gradually increased to approximately 750° F. Starch oil lubricants are slowly vaporized until the fabric is clean. The resulting tape is white.
Tapes are oven treated at approximately 400° F. Starches are partially converted to carbon. The starch oil lubricants partially vaporize and the tape changes color to tan or brown.
Tapes are exposed to a temperature of 450° F. Tape color becomes golden brown. The lubricants partially vaporize and the starches caramelize
Tapes are cleaned in a water bath using scouring agents and enzymes
This treatment is also called S910, A174, Z6020 and A1100. The silane used is 3-(Methacryloxy) propyltrimethoxysilane. This silane is specified for polyester resin systems, but is also effective in epoxy systems. Epoxy resin users sometimes specify 3-glycidoxypropyltrimethoxysilan
e. This is referred to as S920, A187, and Z6040. This treatment is suitable for fabrics treated with phenolic resins.
A latex resin is applied to tapes to lock the weave or knitted stitch and improve stability. The finish is transparent
Tapes are coated with PVA to make the tape stiffer and improve dimensional stability. Customers that sew the glass tapes often specify a starched finish. The PVA treatment is stable at high temperatures.
This is a pigmented acrylic coating on the tape. The color is yellow.
A clear acrylic coating on the tape
This finish may be clear or pigmented. Black pigment is added to provide UV protection for high performance fibers – e.g. Kevlar, Technora
Applied to finished products to enhance temperature range and abrasion resistance.
Pressed under high pressure and heat. Laminated tapes and fabrics are often calendered with adhesive.
Application of a resin on the edge of rolls of narrow fiberglass tapes. Improves efficiency in wrapping rods and coils. May be applied to either untreated or treated tapes.
Application of graphite disbursed in acrylic binder to fiberglass tapes
Water-repellent finish is applied to tape in an aqueous bath. May be applied to either heat-cleaned or cold-cleaned tape.
Resin-compatible Yarns (RCY):
The fiber producer applies a polymeric lubricant to yarns that is compatible with epoxy, urethane, phenolic, and polyester resins. These yarn finishes do not need to be removed from the fabric.