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Plumber's
Nightmare - Part IV Buying the right parts is one thing, but putting it all together is another. There are a number of ways to fasten hose (fuel lines, cooler lines and so on). Some are acceptable while others obviously aren’t.
One of the accepted methods of securing components is with a "cushioned" clamp. Now, cushioned clamps are one solution, but you have to remember that there is more than one variety of clamp. What really is a cushioned line support clamp? In simple terms, it's a clamp that is used to support metal tubing, hose or electrical harnesses. The cushion provides protection to the item being supported by firmly holding the item and preventing or "cushioning" the effects of vibration and abrasion.
When dealing with cushion clamps, you'll usually recognize the name "Adel" clamps. The "Adel" clamp is also referred to as a MS21919 aircraft clamp. Adel Fasteners was established in 1938 in Burbank, California. Since then Adel has become an established industry leader in aerospace clamp and elastomer development. To be quite honest, Adel likely manufactured a large portion of the MS21919 clamps in existence; however there have been other companies, which, over the years, have manufactured them. Nonetheless, the term "Adel clamp" stuck, and it's used interchangeably with all similar varieties of cushion clamps, even if they aren't manufactured by Adel Fasteners. a
d v e r t i s e m e n t The MS21919 clamp is technically called a loop clamp. There are other varieties, but this versatile clamp is the most common in aerospace applications. Common sizes typically range from 1/16-inch to 4-inches in size. When you look at a typical cushion clamp part number, you'll often find a series of suffixes that follow the "MS21919".
Typically, the first will be a "W". That stands for "Wedge". The idea here is that the design of the cushion is such that it prevents something like a small wire in a bundle from being squeezed out during the clamping process. Clamps with sizes below 50 are designed with the wedge feature (more on sizing later). The characters that follow the "W" are also important. The following is a breakdown of clamp suffix codes (these are the two characters that follow the "W"): • CE Corrosion Resistant
Steel Band, Ethylene Propylene Cushion (275° F)
The most common cushion you'll find is the wedge design. The type of cushion material is determined by the environment that the clamp will find itself in. When searching for clamps, you'll often find that clamps with an "F", "G" or "H" suffix (those with low carbon steel bands) are difficult to locate. Why? Simple - they are not recommended for use on a new aircraft design and because of that, have been discontinued for almost twenty years. In other words, don't use them on your car, even if you find a killer deal on a case lot at the local swap meet.
The actual operating temperature of the clamp is determined by the clamp strap and cushion material. Temperatures from -65 degrees Fahrenheit to +450 degrees Fahrenheit can be achieved depending primarily on cushion material selection. If you refer to the above chart, you can see which materials live under specific temperature ranges. In order to recognize the clamps, a series of color codes is incorporated. The following is an alphabetical breakdown of the specific cushion color codes along with pertinent cushion information: • Black (sometimes with blue identity patch): The clamp is manufactured with a Chloroprene cushion. This is a general purpose clamp that can be used in areas that may be contaminated with petroleum-based hydraulic fluids as well as fuel spills. The material has excellent ozone resistant characteristics, but is not resistant to phosphate-ester based fluids. Do not use on titanium tubing. • Blue: Fluorosilicone is the material used for the cushion in this clamp. It is ideal for use in an elevated temperature application where petroleum based fluid contamination may be a factor. The material is unaffected by ozone, however it is not resistant to phosphate-ester based fluids. • Purple: The clamp cushion material is Ethylene Propylene. It is designed for use where contamination by phosphate-ester hydraulic fluid and other synthetic fluids is possible. The material has excellent ozone resistance, but it is not resistant to petroleum based fluids. • Red: This is a Silicone-based clamp cushion, and was only used on clamps manufactured from low carbon steel. It is now obsolete. a
d v e r t i s e m e n t • White (natural): Silicone is used as the cushion material. It is engineered for use in elevated temperature applications where phosphate-ester based fluid and other synthetic fluid may present contamination. This cushion material is not resistant to petroleum based fluids, but it is unaffected by ozone. • Yellow (solid): The cushion material is Nitrile. It is primarily used in applications where it is immersed in fuel or comes in contact with fuel vapors. It has good ozone resistance characteristics, but it is not resistant to phosphate-ester based fluids. In addition, it should not be used on titanium tubing. The final groups of characters you will find on an Adel clamp are numbers that are used to describe the internal diameter of a closed clamp, in increments of 1/16-inch. As an example, clamp number MS21219WDG10 (as shown in the accompany photos) incorporates an aluminum strap inside a black chloroprene cushion and is sized to support a 10/16 or 5/8-inch diameter piece of tube or a wire bundle. Operating temperature is not to exceed 212-degrees F.
Another solution is the line of clamps manufactured by Made For You Products. We've mentioned these before, but let's review the specifics: These clamps are precision molded from a non-conductive 6-6 Dupont Zytel aircraft nylon, however they have no cushion support provision. The Dupont nylon used in the manufacture of the clamp is a space age material that refuses to melt, distort, fade, stain or discolor under normal use. The Zytel material is not affected by brake fluid, coolant, fuel, solvents heat or cold. It's so good, that clamps manufactured by Made For You Products are used in many high stress automotive applications, including Winston Cup cars. Made For Your offers a wide range of clamps in both single place and double place configurations. Single place clamps are obviously designed to hold one piece of wire, tubing or hose in place. Double place clamps (as you might expect) are designed to hold two hoses, hard lines or wire bundles in place.
As far as the single place clamps are concerned, they range in bore size from 3/16" all the way up to 13/16", in 1/16" increments. Double place clamps are another story. Each of the bore sizes can be identical, or they can be ordered in varying sizes. This means that one of the bores in the double clamp can be 15/16" while the other can be 1-1/16". Made For You offers fifteen different varieties of double clamps. You get the picture. An interesting feature of the Made For You clamps is the system of retention. Basically, the clamps are two-piece affairs, split down the middle with indexing pins at the base to register the two halves when joined together. In order to mount the clamp, Made For You includes a 10/32 stainless steel Phillips head fastener with each clamp. Your choice here is to either tap a chassis member or use a nut on the backside (on, for example a tab affixed to the chassis). In either case, the Phillips head of the fastener is actually countersunk into the base of the clamp.
If you're really not sure how many clamps you need, or if you like the thought of having a few extra clamps in your personal inventory, Made For You packages clamps in several different kits. One is geared toward brake line retention, another is designed for hoses (called the "Racing Kit") and another is designed for clamping wiring harnesses. Each kit includes an assortment of appropriate clamps and stainless steel fasteners. Color choices are also another no-cost option from the folks from Made For You. Clamps are available in Black, Blue, Red, Yellow, Gray and Purple. While colored clamps won't make your car any faster or more reliable, they certainly don't hurt in the detailing department. If you haven't gathered
by now, your choices when clamping something in your car are rather
large. If you have a plumbing nightmare on your hands, take a close
look at these clamps (Adel and Made for You). With the prices quoted
for either style of clamp I guarantee you won't get hosed.
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