5 Must-Have Features in a stainless steel chemical pump

Understand the benefits and types of stainless- steel used in hygienic pump construction.  

In food processing, pharmaceuticals, and chemical manufacturing, reliable product transfer is critical. The pumps at the heart of plant operations need to be reliable. A stainless-steel pump offers excellent durability, corrosion resistance, and hygienic operation, making it an ideal choice for process engineers in these industries. Compared to pumps made of other materials, pumps constructed of stainless alloys have lower maintenance costs and a reduced total cost of ownership.

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This blog post explains: 

• Why stainless-steel is the preferred material for pumps, especially in hygienic applications.  
• The various grades of stainless alloys.
• The impact of surface finish on cleanability.
• The benefits of stainless- steel rotors.

Does stainless-steel have good corrosion resistance?

Processing engineers understand that stainless-steel offers excellent corrosion resistance, making it suitable for processing equipment and settings with harsh environmental conditions. Stainless-steel pumps have a significantly longer service life, often lasting up to three times longer than carbon-steel alternatives. In fact, they can have a service life of as long as 30 years.  

How does stainless-steel prevent corrosion? 

The key to stainless-steel’s corrosion resistance lies in its composition. Chromium, present in concentrations above ten percent, forms a passive oxide layer that shields the material from oxidation and rust. Nickel and molybdenum in various grades of stainless alloys enhance resistance against chlorides, acids, and saltwater.  

Common stainless grades used in hygienic pumps include: 

• 304, a general-purpose grade with good corrosion resistance. 
• 316, which contains molybdenum to improve resistance to pitting and crevice corrosion. 
• 316L, a variant of 316 stainless-steel that has a lower carbon content, making it more resistant to carbide precipitation. In carbon precipitation, heat from welding may cause carbides to form, which weaken corrosion protection.
• Nitronic 60, a specialty grade of stainless-steel that combines corrosion resistance with superior wear resistance, making it an excellent material for avoiding galling on pump rotors.

All of these stainless grades are superior to standard carbon- steels for hygienic pumps.

What are the advantages of stainless-steel over steel? 

Compared to carbon- steel, stainless-steel has higher strength and durability along with superior corrosion resistance. It also has a more attractive appearance than carbon- steel and provides superior corrosion resistance. It can withstand many (but not all) aggressive chemicals, high temperatures, and saline environments without coatings or cathodic protection.  

Coating or cathodic protection can extend the life of a carbon- steel pump; however, maintaining the coating requires maintenance and entails a risk of failure. Over time, the coatings crack, peel, and wear off, requiring re-application. A failure of the cathodic protection or coating can lead to rapid corrosion. In contrast, coating a stainless alloy is not so problematic because if the coating wears off, the steel underneath is corrosion-resistant. 

Sometimes stainless-steel is coated to enhance resistance to abrasion and galling. Chromium nitride is a hard ceramic coating that is safe for food processing applications. An added benefit is the coating’s low coefficient of friction, which improves the efficiency of rotating pump components. 

Other significant advantages over carbon-steel pumps include reduced downtime and lower maintenance costs. Construction of stainless alloys enables longer maintenance intervals and less frequent part replacement. What’s more, unlike carbon-steel pumps, pumps made out of stainless-steel clean easily, resist staining, and maintain a polished surface for an extended time.

Maintain hygiene with stainless-steel pumps. 

In industries with strict cleanliness standards, stainless-steel helps maintain hygienic conditions with non-porous surfaces that do not harbor bacteria, mold, or contaminants. The polished finishes of stainless grades reduce surface roughness, preventing bacterial buildup and making cleaning easier.  

The parameter, roughness average (Ra), is a measure of surface smoothness. It quantifies the average deviation from an ideal smooth surface and ranges from 250 to less than 4 µin. Typically, pump interior surfaces have Ra values in the range of 16 - 32 µin.

Cost savings. 

The smooth surface of a stainless-steel hygienic pump resists scaling and buildup, which prevents pump chambers from having narrowed diameters and inconsistent flow rates. By avoiding internal obstructions, these pumps allow for more efficient operation and reduced energy consumption, contributing to operational cost savings.  

In addition, the high level of smoothness reduces friction on the product being pumped. This can contribute to higher flow rates and production efficiencies. 

Plant maintenance managers appreciate that a stainless-steel pump reduces costly downtime due to repairs and replacement. 

All-stainless-steel pump interiors. 

Unlike most pumps, Unibloc® QuickStrip® FoodFirst lobe pumps have stainless-steel rotors, eliminating the chance that a plastic rotor could wear and deposit plastic into the product stream. Furthermore, a unique design eliminates the need for o-rings, eliminating the chance they could become foreign object contamination.  

Unibloc Hygienic Technologies (UHT) developed FoodFirst pumps in response to food manufacturers’ initiatives to eliminate plastic from their processes at a time when the industry was rocked by consumers discovering food contaminated with plastic. UHT is the first pump manufacturer to address this trend with pumps having an all-stainless-steel interior.

Pumps that perform. 

UHT specializes in manufacturing stainless-steel hygienic pumps, including lobe, gear, and AODD types.

• Pump housings are fully machined from a single block of stainless steel, avoiding seams and welds where bacteria could accumulate. Also, this approach eliminates the chance of welding causing carbide precipitation. 
• The stainless grade of 316L enables the pumps to have high resistance to pitting and crevice corrosion even at high temperatures. 
• Nitronic alloy “non-galling” rotors are available for most pump sizes.
• If high grades of stainless steel are not corrosion-resistant enough to handle aggressive chemicals, then Hastelloy (nickel alloy) pumps are available. 

The soft wash industry provides cleaning services for the exteriors of residential and commercial properties. Examples include cleaning stains off concrete driveways or removing mold, moss, and mildew from siding, roofs, and fences. To do so effectively and safely requires the right soft wash pump. 

What is a Soft Wash Pump System?

Regular high-pressure washing systems rely heavily on mechanical removal of stains and can damage surfaces or cause moisture penetration under siding or shingles. A soft wash system uses a gentler application in combination with chemicals to remove stains and debris and minimize the potential for damage. 

Soft wash chemical examples include: 

• Bleach (sodium hypochlorite)
• Algaecides
• Surfactants
• Water

Engineers and equipment designers often struggle to find a pump that stands up to harsh chemicals and produces enough flow and pressure to reach surfaces. Here, we’ll cover five important features to look for in a soft wash system to help your business succeed in this competitive marketplace.

1. Proper GPM & PSI
2. Quiet Operation & Sustainability
3. Chemical Compatibility
4. Pump Longevity
5. Soft Wash Pump Cost

1. Proper GPM & PSI

Gallons-per-minute (GPM) and pressure-per-square-inch (PSI) ratings are critical aspects of soft wash or pressure washer systems. Without the right combination of both, a sprayer won’t have enough vertical and horizontal throw to reach surfaces, which is especially important when cleaning a two- or three-story home. While some pump sprayers can spray that high, they often don’t provide proper coverage at those distances.

Producing enough flow and pressure to evenly reach from ground to eave, without getting on a ladder, is also an important safety factor. Contrary to popular belief, simply increasing the pressure won't get the desired results; having proper flow is what’s needed. 

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The recommended flow and pressure for a soft wash system is about 6.5 GPM at 150 PSI. Paired with the right nozzle, this combination will produce a vertical throw of around 35 feet. If you cut the flow in half to 3 GPM, you’d only get half the vertical throw.

VIEW PUMPTEC SOFT WASH PUMP RECOMMENDATIONS

2. Quiet Operation & Sustainability

Many residential neighborhoods have noise ordinances with a maximum decibel threshold during certain times of the day. Most gas-powered engines that run soft wash sprayers exceed those thresholds. An ordinance might restrict loud noises ‌before 10 a.m. In this scenario, operators might sit idle for a couple of hours, resulting in lost productivity and revenue.

Using battery-powered electric pumps versus gas-powered engines results in whisper-quiet operation. If noise levels and minimizing disruption to area businesses and residents are a concern, use a 12V electric plunger pump system. It can recharge in between jobs without missing a beat and rivals the performance of gas-powered systems.

Another advantage of electric pumps is their ability to comply with legislation restricting gas-powered engines. Sustainability initiatives are gaining momentum across the country, and soft wash system manufacturers and operators will likely need to transition to electric eventually.

RELATED GUIDE: How to Convert from Gas to Electric Pump Systems

3. Chemical Compatibility

The most common chemical used in the soft wash industry is commercial-grade sodium hydrochlorite, a form of bleach. Technicians will use concentrations ranging from 1% for side walks up to 12% for mold and mildew on roofs. Cleaning chemicals are highly corrosive and can easily damage diaphragm pumps made with aluminum or stainless steel components. 

Ideally, pumps should be engineered primarily out of PVC, which has an A-rating for soft wash chemical compatibility. In addition to PVC pump housings, engineers also need to examine other components. For example, we recommend Viton seals vs. Buna, as well as ceramic plungers. Furthermore, valve bodies should be made of Alloy C-276, a highly corrosion-resistant metal alloy. 

RECOMMENDED SOFT WASH PUMP: Pumptec X-PVC Series

4. Pump Longevity

Unfortunately, because of poor chemical compatibility, it’s not uncommon for soft wash spray operators to replace their pumps multiple times throughout the year. In some businesses, cheaper diaphragm pumps are practically treated as disposable because they’re so unreliable, placing a strain on soft wash operations and the environment. 

Sodium hypochlorite-compatible pumps will last significantly longer than traditional diaphragm pumps. The flexible components of diaphragm pumps can easily rupture under high pressure, and they don’t maintain consistent pressure and flow. 

Chemically compatible pumps translate to reduced downtime and labor, and minimize the need for repairs. Another way to extend the life of a soft wash pump is to use proper accessories, like unloader valves. Unloader valves help reduce heat and pressure buildup by activating a bypass mode when the pump runs without pulling the spray gun trigger. 

5. Soft Wash Pump Cost

Directly tied to longevity is the cost of soft wash pumps. However, a value comparison is a better way to approach the topic. You’ll likely spend more for an A-rated soft wash pump, but the savings over the long term will far outweigh the cost difference. If a chemically compatible pump costs four times as much but lasts 10 times longer, there is significant cost savings potential.

With better performance and fewer breakdowns, operators can get in and out of jobs faster and won’t need to spend time making repairs. Employees can spend time on more critical functions that bring in revenue. Likewise, a better performing pump will result in happier customers, leading to more repeat business and referrals. Another consideration is the risk to employees and potential workers’ compensation claims that might result from climbing onto ladders and rooftops. 

When considering a soft wash pump solution, it’s critical to factor in its total cost of ownership. Here at Pumptec, we’ve engineered a powerful and reliable electric soft wash plunger pump, the only A-rated system of its kind in the marketplace. Our X-PVC pump is made of highly resistant materials and engineered to be durable and long-lasting. We’re also developing an innovative unloader accessory that helps further enhance performance and increase longevity. Ask us about it!

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