FAQ - Why Buy OEM Backflow Parts

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If it seems cheap, and too good to be true, it probably is.

Backflow prevention assemblies are health safety valves and must work reliably. Using non-Original Equipment Manufacturer (OEM) repair parts will affect their performance. There are two types of repair parts to consider 1.) soft parts (e.g. rubber/elastomer) and 2.) hard parts (e.g. brass, bronze, stainless steel, and engineered plastics). Both need to be discussed and understanding the impact of using non-OEM repair parts will have on the workings of a backflow prevention assembly. Three issues need to be addressed:

Issue #1. 3rd Party approval (e.g. USC FCCCHR)

Per the USC FCCCHR 10th Edition Manual of Cross Connection Control, Section; “Modifications to backflow prevention assemblies will invalidate the Foundation for Cross Connection Control and Hydraulic Research’s approval. Assemblies must be installed and maintained in the configuration(s) and orientation(s) in which they were evaluated and approved.” Other 3rd party approval/listing agencies have similar language (e.g. ASSE, UL, FM, CSA, NSF, etc.). The key is the word “evaluated”. The assumption that all black colored rubber materials (e.g. EPDM, Nitrile and Silicone) are the same is wrong; even within the same family of rubber. Also the assumption that as long as it has the same dimensions (e.g. o-ring or rubber/elastomer disc) it performs the same is also wrong. The 3rd party approval/listing agencies base their approval/listing on what they have “evaluated”. If any change or modification is made to the design, such as hard or soft parts, the manufacturer must re-submit for the 3rd party evaluation all over again to confirm that the change or modification performs satisfactorily.

For example, changing or modifying something as simple as the type of rubber parts can cause the assembly to not perform the same.

A certain backflow prevention manufacturer has an approved assembly using a Nitrile compound for its rubber parts. Nitrile rubber can have performance issues with some chemicals (i.e., Chloramine) that may be present in drinking water. This chemical can cause this rubber to have a reaction causing it to swell. Years ago, this manufacturer wanted to modify their rubber parts in their assembly to a material that is more resistant to this chemical reaction. They decided to try a silicone rubber material and submitted it to the USC FCCCHR with this rubber modification only. When this version with the silicone material was submitted, to the USC FCCCHR for evaluation, it failed to perform satisfactorily. Note that all other parts and components were kept the same as the approved version, the only change was the rubber material, and it failed the evaluation. So, even when the manufacturer tries to change something as simple as the type of rubber material it may not perform satisfactorily. Again, approval/listing can only be given to the product as evaluated. Changing any soft parts or hard parts with other than original equipment manufacturer (OEM) parts will void the 3rd party approval/listing and more importantly may cause it to not work properly.

Issue #2. Product Liability

All manufacturers carry an insurance policy called Product Liability coverage. This insurance covers damages from products they produce. Key words “they produce”. The cost of Product Liability insurance is based on many variables; what they produce (guns vs candy), how many they produce, and what manufacturing oversights there are. What they produce has to do with the inherent hazard of the product. How many they produce has to do with the amount of potential exposure to a certain hazard. Last issue is manufacturer oversight. Manufacturers of the backflow prevention assemblies must get 3rd party approvals or listings which evaluate the product against an established performance standard. Manufacturers also must make their assemblies using materials meeting various standards (i.e. ASTM, NSF61 etc), which has to do with the quality and safety of the materials. Insurance companies also review the manufacturing process to be sure the manufacturer has some kind of quality control system (i.e., ISO 9001, Statistical Process Control SPC etc.) to ensure the engineering standards and tolerances are being adhered to during the manufacturing process. Like all insurance, the premium is based on the manufacturer’s history and potential exposure. Similar to a bad driver having more expensive auto insurance.

Backflow prevention manufacturers have had insurance claims against their products for many reasons (i.e., water damage etc.).

If a problem arises with the performance of an installed backflow preventer, and damage results (i.e., body or property), the manufacturer must investigate and will pull the assembly from the field for an evaluation. They review to see if it has been field tested according to industry practices (i.e., annual field test history) by a certified tester. They review any maintenance or repair notes. The manufacturer will investigate to determine what caused the failure. For example, dirt and debris are issues of the installation site and not the product. The manufacturer has all parts evaluated and looks for hard part fatigue, soft part (rubber/elastomer and plastic) deformation and anything that could lead to the experienced failure. Part of the investigation may require working with the rubber vendor to identify if the rubber in that backflow prevention assembly is the one that the backflow manufacturer used in their manufacturing process. The reason a manufacturer may have to work with the rubber vendor is that the formulation of the rubber they buy is a trade secret of that vendor and they may be the only one who can properly identify the type and formulation of the rubber.

Although a backflow prevention assembly manufacturer will know the family of rubber (Buna N, Nitrile, EPDM etc.) they use, they may not know the exact formulation of that rubber material they buy. During the design stages of a backflow preventer, the design engineers meets with the rubber vendor and evaluates the product design to pick the appropriate rubber for that assembly. For instance, there are over 100,000 formulations for Buna N which is a very popular and durable rubber. Of the 100,000 formulations only about 10% may be considered food grade or able to be used in a potable product. Conformance to material standards like NSF 61, assures no unwanted chemicals will leach from the rubber or other parts into the drinking water. So once the manufacturer evaluates and chooses their rubber, installs it into their design, and submits it for 3rd party approvals or listings, they cannot change the formulation of the rubber they use or they must go through evaluation all over again. They have to rely on their rubber vendor to supply the same rubber each time they order it.

The key point is if the rubber is changed with a non-OEM part, it is not as “they produced it”. The assembly now becomes a product of whomever made the change and put the different parts into the assembly, and all approvals, factory coverage and warranties are null and void.

The manufacturer is no longer part of the investigation into an insurance claim because it is no longer their designed assembly. It is like a person putting a Ford engine into a Chevy having a mechanical issue and expecting Chevy to cover the car under a warranty. The coverage for product liability performance issues now falls on whomever put the non-OEM parts into the assembly; just as it would fall on the person who put the Ford engine in the Chevy car. The cost savings of using non-OEM parts is nowhere near commensurate to the liability one assumes by using a non-OEM part for hard or soft parts.

Issue #3 Performance:

Before a backflow prevention assembly is ever purchased, a lot of design, review and approvals/listings go into the final product. All this analysis creates a lot of data on how this product should work. Yes, the manufacturer has an insurance policy just in case. We don’t plan on getting into a car accident, but just in case, we keep auto insurance. So by the time they are ready to sell these backflow prevention assemblies to the public, they have a pretty good idea how they will perform in the field, which is backed up by the 3rd party approvals/listings performance review and evaluation. Someone unaware of the consequences now comes along and says, I have a flat piece of black rubber, I can cut out a disc, or I have a box of different size O-rings, I can change them for a lot less money and nobody will ever know. The change of rubber may change performance to some degree. The question is how much will it change. The only way to answer that question is to evaluate this modified product all over again. Obviously, that is not what the non-OEM part user is trying to achieve. They only think that they are saving money.

Rubber products are made from various oils, fillers and curing agents. For instance, the reason there are so many formulations of Buna N on the market, is each little change in the formulation has a performance outcome the rubber vendor is trying to achieve. For example, a certain backflow prevention manufacturer first started the evaluation of their product with a standard Buna N elastomer. While under evaluation at the test laboratory, the rubber began to develop an orange peel texture. The engineer checked with the rubber vendor and was told to use the same rubber but change to one with a peroxide cure instead of a sulphur cure. By making this change in the curing process, which is not visible to the eye, the product was better for its application and now was able to pass the 3rd party evaluation. Again, rubber vendors make rubber for many industries and applications, and a change in family, formulation or even curing process will affect performance. Making check valve elastomer discs out of a similar rubber does not mean it will seal and perform the same as the OEM repair part. Even the pliability (i.e. flexibility, shore hardness) can affect performance.

People that sell non-OEM parts usually go to an o-ring supply house or a rubber vendor and buy something that looks the same dimensionally, but it is impossible to be sure it is the same chemically, and if it is different, it will perform differently. The issue now becomes where the rubber is used. Many RP assemblies have an o-ring in their relief valve. There are two types of o-ring applications; dynamic and static. Static, as the name implies, an o-ring that is placed in position and doesn’t move, as in a check valve cover application. The dynamic o-ring on the other hand, is one that has movement across its face or may slide through normal use of the product. The relief valve design of most RP assemblies on the market today uses some sort of dynamic o-ring (e.g. 4A-200, 825Y, 009, 975XL). If this o-ring swells in any way it will affect the relief valve opening point by squeezing on the relief valve stem or increasing the breakaway friction also causing the relief valve opening point to change. O-rings have a standard sizing sequence, but there are many different rubber formulations made. Buying a standard o-ring with the same size as a factory o-ring is very easy to do, but buying one that has the same rubber formulation and performs the same, is much harder to accomplish.

Most check valve and relief valve discs are molded to provide a more uniform surface and performance. This requires a relatively expensive production mold to be made to form the discs. Discs can also be cut from a sheet of rubber; this is typically a cheaper method since it doesn’t require a mold, only a cutting form, similar to a cookie cutter. Cutting check discs out of a similar rubber material does not mean it will seal and perform the same as the factory repair part. Variables such as the shape of the seat, spring tension, all are matched to the type and softness of the rubber. Any change in these variables can cause the check valve or relief valve to not perform the same. These changes can also cause the length between repairs to be shortened because of performance.

The introduction of non-OEM hard parts is just as problematic. A common example is the replacement of stainless steel (SS) bolts or washers inside an assembly. Flat stainless steel washers are often used as disc retainers inside assemblies. Stainless steel bolts or screws are commonly used to hold check and relief valve modules together. Stainless steel is graded in a numeric designation such as 300 or 400 series. The amount of chromium and nickel are two variables that give SS its important properties of hardness and corrosion resistance. Even between grades within the same range (304 vs 316) there can be significant performance changes and corrosion resistance. Flat washers are used when force needs to be exerted over a larger area than the bolt head can achieve. The thickness, diameter, end shape, and grade of the SS washer all make a difference in its performance. When this washer is used to hold a disc into a disc holder, it must be evaluated to assure proper performance. If the washer does not properly retain the disc under all flow conditions, and the disc is dislodged from the holder, the check or relief valve will not work properly even though the washer may appear to be the same. The type of SS is another important issue. When screws or bolts are replaced with non-OEM parts, the grade of SS can cause corrosion issues inside the assembly.

The usual reason an unaware technician will introduce a non-OEM part is to save cost. The cost of original factory repair parts may seem excessive. Manufacturers have to recover their costs and must be able to show a profit to their shareholders. The cost of original factory repair parts for older assemblies will tend to cost more than current models. This has a lot to do with production costs. For instance, if a piece of rubber costs $5, then the manufacturer must determine how many they will produce in a specific repayment time. Let’s assume they want to recover their costs in one year. The manufacturer normally has a minimum order quantity that their suppliers will require, let’s assume that is 1,000 for this example. This means regardless of their usage, they are required to order a certain amount. If the piece of rubber is $5, and they order 1,000, their cost for that item is $5,000. Let’s assume the manufacturer requires a 10% profit. This means they have to sell these 1,000 parts for $5,500. Now comes the time factor. This rubber part, in a presently produced assembly, may sell 1,000 in a year very easily so they would charge $5.50.

  • (1,000 pieces X ($5 X 10%) = $5500 ÷ 1,000 = $5.50)

If the item is for an older model or a size unit that doesn’t sell as many, the cost will be different. Let’s say they only sell 250 of these items in one year. Now they must get their return on investment from 250 pieces meaning the selling price is now $22.00.

  • (1,000 pieces X ($5 X 10%) = $5500 ÷ 250 = $22.00)

You say that is not fair they still have 750 pieces in stock, but yes there is a cost called holding costs and product degradation that can happen over time. This degradation may require them to throw the item away rather than sell it because it is too old. Manufacturers wish they could buy just the one part, sell the one part, and start over again. This is not a cost effective way of production. Manufacturers produce 1,000’s of an item at a time and hope their sales force gets out and sells them. This has to do with marketing, another cost of doing business along with many others such as buildings, payroll, production facilities, warehouses etc. etc...

The question may be asked; Why should I have to pay what appears to be relatively expensive amount for OEM Parts, when I can buy a similar product at a much cheaper price, and nobody will know what I put inside the assembly? A water purveyor requires a backflow prevention assembly to be installed to protect against an identified hazard. As a repair technician, you want to be sure you are not liable for any damages from your actions. Whether it is from negligence (bad work) or fraud (representing non-OEM parts as genuine), using non-OEM parts opens the repair technician to a myriad of problems. The cost savings is nowhere near commensurate with the liability being assumed. By buying and using only OEM repair parts, you assure the 3rd party approval is maintained, the manufacturer’s warranty and product liability is maintained, and performance of the assembly will be as evaluated during the approval process. Because of that, you will reduce your liability accordingly and just as importantly, the assembly will work when needed to stop a backflow event.