Why MetCheck 316 Stainless Steel RPZ & DCV Backflow Preventers Are Worth Considering

Why MetCheck 316 Stainless Steel RPZ & DCV Backflow Preventers?

When selecting a large backflow preventer, compliance and purchase price are naturally important. But for an asset expected to remain in service for many years, there are other questions worth asking.

How will the valve handle the water it's installed in? How much pressure will it consume? How easy will it be to service? And what will it actually cost to own over its working life?

These considerations become particularly important in hospitals, food and beverage plants, industrial facilities, fire systems, coastal environments and sites operating on aggressive bore water.

The MetCheck RPZ and DCV range takes a different approach to traditional epoxy-coated ductile iron backflow preventers, combining 316 stainless steel construction, proven Tri-Force check technology and a design focused on long-term serviceability.

The result is not simply a stainless steel backflow preventer. It is a valve worth considering where corrosion resistance, hydraulic performance, maintenance and lifecycle return on investment all matter.

1. Corrosion: What Happens Inside an Epoxy-Coated Valve?

Epoxy-coated ductile iron is widely used in larger backflow preventers and can provide good service in suitable conditions.

Its corrosion protection, however, depends on the integrity of the coating.

Over time, epoxy can be compromised through handling, installation, servicing, debris, ageing and normal operating conditions. Once water reaches the underlying ferrous body, corrosion can begin beneath the coating.

This can eventually result in:

• Bubbling and blistering of the epoxy
• Coating delamination
• Internal rust and scale formation
• Flaking of coating and corrosion products
• Corrosion around check seating and retaining surfaces

The issue isn't necessarily what can be seen on the outside of the valve.

It's what can be happening internally.

Once rust scale or coating material breaks free, it can move downstream through the water system.

Depending on the facility, that can potentially contribute to fouling of:

• Thermostatic mixing valves (TMVs)
• Solenoid valves
• Strainers
• Control valves
• Smaller backflow devices
• Process equipment and other small-waterway components

In a building containing dozens or hundreds of downstream water-control devices, deterioration of one large upstream valve can become a much wider maintenance issue.

2. MetCheck Uses 316 Stainless Steel Instead

MetCheck approaches corrosion differently.

Rather than using a protective coating over a ductile iron main body, the MetCheck body is manufactured from 316 stainless steel.

That means the corrosion resistance comes from the valve material itself rather than relying on an epoxy barrier remaining intact throughout the valve's service life.

There is:

• No ductile iron main body to rust
• No internal epoxy lining to blister
• No epoxy coating to delaminate into the waterway
• Greater inherent resistance to many aggressive environments

This doesn't mean stainless steel is indestructible or maintenance-free. It simply removes one significant deterioration mechanism from the backflow assembly.

3. Why 316 Stainless Instead of 304?

304 stainless steel is widely used throughout the water industry and performs very well in many environments.

However, 316 stainless contains molybdenum, which provides improved resistance to chloride-induced pitting and crevice corrosion compared with standard 304 stainless.

That difference can become important in environments involving:

• Chlorides
• Coastal atmospheres
• Salt spray
• Wet plant rooms
• Industrial water
• Treated water
• Food-processing facilities
• Certain groundwater supplies

When the valve is expected to remain part of a building or plant for many years, selecting 316 provides an additional level of corrosion resistance worth considering.

4. A Strong Option for Aggressive Bore Water

Not all bore water is corrosive, and groundwater chemistry varies considerably between sites.

However, some bore supplies can contain elevated levels of chlorides, dissolved salts, minerals and other constituents that make them considerably more aggressive towards metallic components than a typical municipal water supply.

In these installations, material selection becomes particularly important.

With an epoxy-coated ductile iron valve, corrosion protection depends on keeping aggressive water separated from the iron substrate. If the coating becomes damaged internally, deterioration can accelerate at the exposed area.

A solid 316 stainless steel body provides a very different material platform.

This makes MetCheck particularly worth considering for:

• Rural water supplies
• Industrial bore systems
• Irrigation infrastructure
• Food-processing plants using groundwater
• Wash-down supplies
• Commercial facilities with private water sources
• Sites known to experience premature corrosion of conventional valves

Water analysis should always guide material selection where particularly aggressive groundwater is present, but 316 stainless can provide a significant advantage where corrosion is already a known problem.

5. 316 Stainless Internals as Well as the Body

The body material is only one part of a backflow preventer.

MetCheck also uses high-grade stainless steel throughout its internal components.

This is important because springs, check components and seating areas are continuously exposed to the water passing through the valve.

Using similar high-quality materials throughout the wetted assembly helps reduce the issues that can arise from combining multiple dissimilar metals in the same environment.

The objective isn't to create a valve that never requires servicing.

Backflow preventers are mechanical safety devices and will always require inspection, testing and maintenance.

The objective is to start with a valve and internal components capable of remaining serviceable for a long operating life.

6. Tri-Force Check Modules: Proven Reliability and Exceptional Flow

Corrosion resistance is one part of the MetCheck story.

Hydraulic performance is another.

MetCheck RPZ and DCV assemblies can utilise the Tri-Force spring check module, a proven large-bodied check design known for reliability, straightforward servicing and exceptional flow characteristics.

The Tri-Force design is particularly interesting from a hydraulic perspective.

Once fully open, approximately 6 kPa differential pressure is required to hold the check open.

This allows the check to provide high flow while minimising unnecessary pressure loss through the backflow assembly.

Why does that matter?

Every backflow preventer introduces some resistance into the pipeline.

On an ordinary water service, a few additional kilopascals may not be significant.

On a fire hydrant system or another high-flow installation, they can be extremely important.

Hydraulic engineers are often working with a limited amount of available supply pressure. Every component — pipework, bends, meters, strainers, valves and the backflow preventer — consumes part of that pressure.

Reducing the pressure consumed by the backflow assembly leaves more available for the system downstream.

The benefits can include:

• Lower pressure loss
• Excellent flow capacity
• More available downstream pressure
• Greater usable litres per second
• Additional hydraulic design margin

For hydrant and high-flow applications, this can be one of the most important reasons to consider MetCheck.

7. Tri-Force Checks Are Designed to Be Serviced

High flow is useful, but long-term serviceability is equally important. The Tri-Force is a large-bodied check module designed so that technicians can access and maintain it rather than automatically treating the entire check as a disposable component.

Wear components can be replaced as required.

This can provide:

• Straightforward servicing
• Replaceable wear components
• Reduced requirement for complete check replacement
• Lower spare-parts costs
• Less material being discarded
• Longer useful life from the original check assembly

On larger backflow preventers, these differences become increasingly important.

A serviceable check assembly gives the asset owner the opportunity to maintain the original equipment rather than progressively replacing expensive major components.

8. Designed with the Backflow Technician in Mind

Every testable backflow preventer will eventually require maintenance. How easily technicians can get inside the valve therefore matters.

MetCheck uses a double-clamp body arrangement to provide access to its internal check assemblies.

The practical advantages include:

• Fast access to the checks
• Straightforward disassembly
• Fewer components to remove
• Easier internal inspection
• Simple reassembly
• Reduced servicing time

This may sound like a relatively small feature when initially specifying a valve. After years of scheduled testing and maintenance, it can become a significant one.

In hospitals, food plants and industrial facilities, shutdown windows may be limited. A valve that can be inspected and serviced efficiently helps reduce disruption to the facility.

9. Why MetCheck Suits Hospitals

Hospitals have particularly complex water systems. Downstream of the main incoming supply there may be substantial numbers of:

• TMVs
• Solenoid valves
• Control valves
• Strainers
• Specialist equipment
• Additional backflow preventers

Many of these components contain relatively small waterways and moving parts. Keeping rust scale and deteriorating coating material out of the downstream system is therefore a worthwhile consideration.

A 316 stainless MetCheck assembly removes the epoxy-coated ductile iron main body from the equation while providing serviceable internal check assemblies.

For hospital asset managers, the benefits are less about having a visually impressive stainless valve and more about:

• Long-term corrosion resistance
• Reduced potential for valve-generated rust and coating debris
• Straightforward scheduled servicing
• Serviceable check assemblies
• Reduced risk of body corrosion making the valve unrepairable
• Long-term asset management

The aim is not to eliminate maintenance.

It is to make the backflow preventer itself less likely to become the cause of additional maintenance elsewhere in the system.

10. Why MetCheck Suits Food & Beverage Facilities

Food and beverage facilities can be demanding environments for water infrastructure.

Plant rooms and processing areas can involve:

• Regular wash-down
• High humidity
• Wet environments
• Chlorides and salts
• Cleaning processes
• Temperature changes
• Aggressive water supplies
• Tight production shutdown windows

Some facilities also operate partially or entirely from bore water, adding another consideration around water chemistry.

The combination of 316 stainless construction, corrosion-resistant internals and straightforward servicing makes MetCheck well suited to these environments.

And when a production shutdown carries a significant cost, being able to service the backflow assembly efficiently can be just as important as the cost of the replacement parts.

11. Coastal and Corrosive Environments

The environment outside the valve also matters. Coastal facilities can expose valves and pipework to chloride-laden moisture and salt spray.

If the external epoxy coating of a conventional ductile iron valve is damaged, corrosion can begin from the outside as well as internally.

A 316 stainless body provides corrosion resistance throughout the material rather than depending solely on a surface barrier.

That can be particularly useful for:

• Coastal buildings
• Marine facilities
• Exposed plant rooms
• Food factories
• Industrial sites
• Wet processing areas
• Bore-water installations

Again, 316 stainless isn't immune to every possible environment, but it provides a strong material choice where corrosion is an identified concern.

12. RPZ and DCV Options

MetCheck is available in both Reduced Pressure Zone (RPZ) and Double Check Valve (DCV) configurations.

The correct device needs to be selected according to the hazard classification, applicable standards and requirements of the water supplier or approving authority.

RPZ

An RPZ incorporates two independently operating check valves with a relief zone between them and is selected where the required hazard protection calls for an RPZ device.

DCV

A DCV incorporates two independently operating check valves and is used where the relevant hazard classification permits double-check protection.

The required protection level determines the device.

The MetCheck construction philosophy remains similar across the range:

316 stainless construction, proven check technology and long-term serviceability.

13. Correct Earthing Remains Important

316 stainless addresses many corrosion concerns, but it should not be considered immune to stray electrical current. This is particularly relevant in systems incorporating electric pumps.

If current leakage causes the valve or pipework to become part of an unintended electrical path, electrochemical attacks can damage metallic components. Over time, even a stainless body can develop severe pitting or pinholes.

Correct electrical bonding and earthing of the backflow preventer, strainer and associated installation is therefore important.

This is an important distinction:

316 stainless helps address material and environmental corrosion. Correct earthing helps protect against electrical corrosion.

Both should form part of a well-designed installation.

14. The Lifecycle ROI Is Where the Difference Can Become Significant

A large backflow preventer shouldn't necessarily be judged by purchase price alone.

For an asset that could remain in a facility for 10, 15 or 20 years, a more meaningful calculation is:

Purchase + servicing + replacement parts + labour + downtime + downstream maintenance + eventual replacement.

This is where the MetCheck design can provide a strong lifecycle return on investment.

The 316 stainless body is intended to remain serviceable rather than depending on an epoxy barrier protecting a ferrous substrate.

The Tri-Force checks are serviceable, allowing wear components to be replaced without unnecessarily replacing complete check modules.

The double-clamp body arrangement provides straightforward technician access, helping reduce the labour and downtime associated with routine maintenance.

Together, these characteristics can contribute to:

• Longer useful valve-body life
• Lower risk of corrosion making a large valve uneconomic to repair
• Fewer major replacement components
• Lower ongoing parts expenditure
• Reduced potential for rust and coating debris affecting downstream equipment
• Faster servicing
• Shorter shutdown periods

Delayed complete valve replacement

15. The Larger the Valve, the More Lifecycle Cost Matters

Lifecycle considerations become particularly important with large backflow assemblies.

Replacing a large RPZ or DCV doesn't simply mean purchasing another valve.

Depending on the installation, replacement can involve:

• Isolating the water supply
• Draining the system
• Technician and contractor labour
• Lifting and handling equipment
• Removing existing pipework
• Installing the replacement valve
• Pipework modifications
• Recommissioning
• Backflow testing
• Operational disruption

In a hospital or food-processing facility, the cost associated with the shutdown itself can potentially exceed the cost difference between two valves at the time of initial construction.

This is why the MetCheck value proposition is better considered over the working life of the asset, rather than solely at tender stage.

A higher-quality, maintainable valve can provide better value if it reduces major repairs and delays the need for complete replacement.

16. Four Areas Worth Considering When Comparing Backflow Preventers

When comparing MetCheck with other large RPZ or DCV assemblies, it can be useful to look beyond the specification sheet and consider four areas.

1. Material

What is the body actually manufactured from, and what happens if its protective surface is damaged?

With MetCheck, 316 stainless steel provides the corrosion-resistant material rather than relying on an epoxy-coated iron substrate.

2. Hydraulic Performance

How much pressure does the backflow assembly consume at the required flow?

The Tri-Force check design provides exceptional flow characteristics with low resistance once fully open.

3. Serviceability

When a check eventually requires maintenance, can it be serviced efficiently or does a major assembly need to be replaced?

MetCheck is designed around accessible, serviceable check modules and straightforward clamp access.

4. Lifecycle Cost

What will the valve cost to own over the next decade or two — not simply what does it cost today?

This includes parts, labour, downtime, downstream maintenance and eventual replacement.

Where Does MetCheck Make the Most Sense?

MetCheck RPZ and DCV backflow preventers are particularly worth considering where one or more of the following apply:

• Corrosion is already a known issue
• Aggressive or corrosive bore water is present
• The installation is coastal
• High flow rates are required
• Available system pressure is limited
• Hydrant performance is important
• The valve will be maintained for many years
• Maintenance shutdown windows are short
• Downstream equipment is sensitive to debris
• Long-term lifecycle cost matters

That can make the design particularly relevant to:

Hospitals | Food & beverage plants | Industrial facilities | Fire systems | Bore-water systems | Coastal installations | Commercial buildings | Critical water infrastructure

A Different Way of Looking at Backflow Selection

There is no single backflow preventer that is ideal for every installation.

The required hazard protection, approvals, water chemistry, hydraulic requirements, installation conditions and budget all need to be considered.

But it is worth looking beyond the initial purchase price.

With MetCheck, the benefits come from several design choices working together:

316 stainless steel provides a corrosion-resistant body and internal material platform.

Tri-Force check technology provides proven reliability, excellent flow characteristics and straightforward servicing.

Double-clamp construction makes routine access simpler for technicians.

And serviceable components provide the opportunity to maintain the asset rather than unnecessarily replacing major assemblies.

For an installation expected to operate for many years, particularly in corrosive bore water, coastal environments, hospitals, food factories and high-flow systems, those differences can have a meaningful impact on reliability and whole-of-life cost.

The real question isn't simply, “What does the backflow valve cost?”

It is:

“What will this backflow valve cost to own, maintain and eventually replace over the life of the facility?”

That is where the lifecycle return on investment of a well-selected, corrosion-resistant and serviceable backflow preventer becomes much more important.