作者： sansun01

Automated stem seat valves are workhorses in the sanitary food and beverage process industries and for good reason.  They are versatile, easily cleaned in place, low maintenance and relatively cost effective.  They are available in a wide range of sizes.  Properly applied, they can operate trouble free for long periods. Having said that, if you have spent much time in a sanitary processing facility, you have probably experienced the sound of a sanitary seat valve slam shut resulting in the process line shaking back and forth.  Often this is a result of an improper application of the valve.  Sanitary seat valves are designed to close against the flow (for standard shut off valves, this means in the bottom out the side).  If they are piped with the flow, they will often slam when actuated.

For a standard shut off valve most manufacturers offer a reverse acting model if piping consideration do not allow piping the valve in the optimal position.  For divert valves, this is not always the case.  Sanitary divert valves are used all over sanitary process plants.  Normally they have one inlet and two outlets, allowing flow to go in one of two directions.  This process is often reversed as well. The standard configuration is to have the inlet and one outlet on the side of the valve and the second inlet on the bottom. The valve stem has two seats that operate in the middle part of the valve sliding from one seat to the other to divert the flow.  Using a standard loaded actuator, this configuration almost guarantees that the valve will slam in one the two operating conditions.  How do you fix this?  sansun valve has an answer.

SSD05 is one of the most configurable valve lines on the market.  Their traditional type SSD05 series divert valve has 12 different configurations.  But these all have the same drawbacks as far as their potential for “valve slam”. To solve this problem Waukesha also offers the SSD05 line of sanitary divert valves.  These valves are configured so that all of the ports are on the same plane (8 configurations in all).  The inlet comes into the middle of the valve with the two outlets on the top and bottom (or vice versa for reversed flow)

On the SSD05 divert valve, the valve stem goes from the actuator all the way through the valve body.  Both ends are sealed with an o ring.  This allows the valve seats to be in both the upper and bottom chambers of the valve, allowing the seats to close against the flow at all times.  The result, no slamming!

You are going to pay a little more for the sansun sanitary divert valve than you would for the SSD05.  But isn’t that well worth it to keep your process lines from shaking all over the place?  We think so, considering excessive vibration can lead to instrument damage and inaccuracies.

The sansun sanitary valves are available in sizes 1” through 6”.  This is an extremely well built product.   The W60 valve is very modular.  All of the valve bodies are machined from bar, not castings.  This results in a very wide choice of configurations.  There are also multiple seat material options as well as a very large choice of controls/switch options. Control tops for the entire SSD05 series have also been modularized, with the SSD05 using the clear WCB top also found on the other SSD05 seat valves, the SSD15 mixproof valves, and even the 200 series butterfly valves.

So if you are looking to use automated seat valves in your process and you would prefer your pipes not to shake, consider the sansun when it comes to divert valves.  If you have questions on this topic or any other topic regarding sanitary process, contact one of our sales engineers.  We will do our best to help.

In Europe and the UK, the term sanitary piping defines the plumbing used to convey potable water systems as well as waste water generated downstream of those water systems, i.e.  the plumbing used to bring water into your house and the associated waste plumbing.  These systems can be made from carbon steel pipe, PVC pipe or copper tube.   Other English speaking countries such as Australia and New Zeeland also refer to sanitary piping in this way.

The term hygienic piping in these countries refers to the highly polished, stainless steel high purity tubing systems used in process piping in biopharmaceutical, food, beverage and dairy facilities.  All of the different hygienic systems have special connections designed to allow the systems to be cleanable and eliminating bacterial entrapment areas.

3000 miles to the west, in North America, linguistically we take a different approach.  You rarely see the term hygienic piping used.  Instead we use sanitary piping as a dual purpose term.  It refers to both high purity systems as well potable water and waste water systems.  Does it make sense to use the same term in conjunction with the high purity piping systems used in pharmaceutical plants as well as the plumbing in your house downstream of the bathroom?  Not really.  But that is what we do.

There are some difference between European hygienic fittings/piping and the North American sanitary high purity fittings/piping.  But they have a lot of things in common.  They are all either 304 or 316L stainless steel thin wall tubing  The buttweld connections are designed to be TIG fusion welded together.  They all have interior surface finish finishes polished to precise specifications.  Their mechanical connection systems are designed to yield a crevice free joint that is cleanable and has no areas for bacterial entrapment .

This is Considered Part of a Sanitary Piping System in both the US and in Europe

It seems to us that the European practice of delineating the terms hygienic piping and sanitary makes more sense than the North American practice of throwing all of these terms for sanitary piping in the same bucket.  But we don’t make the rules, we just play by them.  Either way, if you need help with hygienic, sanitary high purity piping systems, contact us.  We are pretty good at this.

Its excellent resistance to aggressive environments, wear and direct sunlight makes it suitable for either indoor or outdoor use.

The butterfly valve can be operated automatically with an actuator or manually with a handle.

The handle blocks the valve in the “open” or “closed” position, although there are also other models with intermediate positions.

The actuator transforms the axial movement of the piston into a 90º rotary movement which it transmits to the disc.

Other options for the butterfly valve are multiposition handle, mini multiposition handle, 4-position handle, 2-position handle, lockable handle, micrometric handle, pneumatic actuator.

Butterfly valves, whether manually or automatically operated, can be used in most liquid product applications in the food-processing, pharmaceutical and chemical industries.

Users of sanitary stainless steel fittings, tubing, valves and various other types of sanitary process equipment are presented a wide variety of interior surface finish choices in today’s marketplace.  What is considered clean, hygienic or sanitary in some markets may not be in others. Add to that the fact that the terminology of measuring surface finishes has changed over the years and you end up with a lot of confused users.  We will try to bring some clarity to these issues in this post.

History

The world of sanitary process tubing, fittings and process equipment originated in the dairy industry.  Over time these products have migrated into a multitude of other industries including food, biopharmaceutical, beverage, personal care and other industries concerned about cleaning their process systems.  For years surface finishes were measured by the grit rating of the final abrasive used in the mechanical polishing process.  What was acceptable in the food and dairy industry was 150 grit.  Pharmaceutical users often specified 180 grit or higher.

As profilometers became commercially available, surface finish measurement started to be categorized by measuring the final surface finish itself.  A profilometer is an instrument that measures the actual metal surface by dragging a stylus across the metal a predetermined length, measuring the distance between the peaks and valleys of the surface.  Initially the values were stated using the RMS (Root Mean Square) method.  Eventually the industry standardized on stating the values in RA, and arithmetic average. Ra values are generally 11% less than RMS values.  In the US Ra is measured in micro-inches, in other
parts of the world in micro-meters.

Surface Finishes:   Ra vs.  Grit

Ra(micro-Inches)             Grit

32                                           150
20                                           180
15                                           180+electropolish
10                                           240+electropolish
10                                           320
5-10                                       320+electropolish

Today

The standard sanitary internal surface finish in the food, dairy and beverage markets is 32Ra.  This has been determined by the 3A (the organization that sens standards for the dairy industry) to be the minimal standard for piping.  The pharmaceutical industry uses a broader range of surface finishes as determined by the end user.  Most biopharmaceutical company specifications now adhere to the ASME BPE standards.  The ASME BPE categorizes 7 different surface finishes, 4 for mechanically polished fittings/tubing and 3 for mechanically polished plus electropolished.

Mechanically Polished

Surface Designation       Maximum Ra

SF0                                         No finish requirement
SF1                                         20Ra
SF2                                         25Ra
SF3                                         30Ra

Electropolished

Surface Designation       Maximum Ra

SF4                                         15Ra
SF5                                         20Ra
SF6                                         25Ra

ASME BPE standards have additional standards for acceptability as well as standardized dimensions.

Today there are a broad variety of sanitary fittings and tubing on the market available with 32Ra interior surface finishes, included buttweld and many different types of sanitary clamp connections. ASME BPE fittings are commercially available in the SF0(no polish),  SF1(20Ra) and SF4(15Ra+electropolish)as standard in both buttweld and sanitary clamp configurations.   Other surface finishes would normally require a special order.   Ironically, commercial sanitary tubing is no longer offered in 32Ra.  The tubing manufacturers have honed their manufacturing processes to the point that the minimum surface finish they offer in 20Ra, considerable better than the minimal 3A standards.

We have decided to write a series of blog posts on the various types of sanitary valves on the market covering their various methods of operations, their process benefits and limitations and their relative costs.   Today we thought we would start with one of the most simple and least expensive examples, the sanitary butterfly valve.

Principles of Operation

The sanitary butterfly valve consists of a round, split stainless steel body and a stainless steel disc which is positioned in the center of the pipe. The disc (“butterfly”) has rods on the top and bottom that position the disk in the body and attach to a handle or actuator on the outside of the valve.   A rubber donut like seat is positioned between the body and the butterfly.  Turning the actuator/handle turns the disc either parallel or perpendicular to the flow. Different from a ball valve, this disc is permanently existing within the flow; consequently a pressure drop is always induced in the flow, regardless of valve position.

The valve seal is affected by the compression of the disk against the interior of the rubber seals.  The rubber seal also seals the stem that attaches to the handle.   Seal materials are normally available in EPDM, Viton and Silicone.  Most sanitary butterfly valve manufacturers supply sizes from 1” through 4”.

Pressure Ratings

The sanitary butterfly valve is clearly not a high pressure valve.  Listed below are typical pressure ratings.

Size        Pressure Rating @70 F)               

1”                            140 PSI

1 1/2”                   140 PSI

2”                           140 PSI

2 1/2”                   110 PSI

3”                           110 PSI

4”                            85PSI

Automation

Most sanitary butterfly valves can be highly automated.  Most manufacturers offer stainless steel pneumatic linear actuators for all sizes.  Many offer different switch packages to mount to their actuators.  Also, as they are ¼ turn valves, sanitary butterfly valves can be automated with double rack and pinion pneumatic actuators.  There is a huge offering of different ¼ turn actuators on the market and an equally large offering of switch packs to go along with them.  You can also fit electric ¼ turn actuators to them.

Other Sanitary Butterfly Valve Features and Benefits

 While the operating principles of the butterfly valve are relatively straight forward, used ubiquitously in both in industrial and sanitary applications, each manufacturer has their own unique offerings. First, it’s important to understand that the butterfly valve market could be considered a commodity market. There is always a cheaper one out there. That being said, for best performance it is critical to select a high performing valve that suits your process requirements at a fair price.

One unique feature that customers should be mindful of are handle style and material type. Not every manufacturer offers 304 and 316L valves. MTRs and C of C’s can also be difficult to obtain. That’s where a good distributor can help you identify the best valve manufacturer for your application.

Continually, not every manufacturer offerings a wide variety of manual BFV handles. Some common handles that are available in addition to the standard quarter turn handle are the infinitely adjustable w/ lock out hub, a pad lock ready handle to lock the valve in place, 9 position handles, and even manual handles equipped with proximity switches.

Other considerations are end connections and valve footprint. Butterfly valves are generally wafer style valves, that being said, overall dimensions should still be verified. End connections available include Triclamp, I line, and butt weld. One important consideration if you will be welding a valve into the process line is maintaining the valve. While rarely done, you do not want to be cutting the valve out of the line every time you need to change the seat. One product offering by APV is a flanged type valve that is welded and then bolted into line to allowing benefits of a weld in valve with the ability to maintain the internal valve wafer.

Are Sanitary Butterfly Valves Clean?

The word sanitary has different meanings for different users.  Are sanitary butterfly valves clean? Sort of, depending upon your application. The fact that they are offered with sanitary clamp ends and are made from polished stainless steel and FDA approved elastomers makes sanitary butterfly valves relatively clean.  They are a straight through valve so they are relatively drainable.  But in some industries, the seals around the stems on the disks are problematic.  They often don’t get completely clean in a CIP cycle.  So to truly clean the valves, they must be disassembled.  Because of this, butterfly valves do not get 3A approval and you rarely see them in biopharmaceutical applications.  The ASME BPE does not even address them.  But we do see them in food and beverage applications on a daily basis.  In the end, what is clean enough is often determined by the end user.

 Conclusion

Here in a nutshell is our opinion of the pluses and minuses of sanitary butterfly valve

Plus                                                                                       Minus

Inexpensive                                                                       Cannot take high pressure

Easily automated                                                             Won’t completely clean during CIP

Quick Turn Around                                                          Difficult to find in ½” and ¾” sizes

Easy to repair/few spare parts

So that is our take on the sanitary butterfly valve.  In future posts we will present overviews of the other commercially available sanitary valves including ball valves, diaphragm valves, seat valves, mix-proof valves as well as some of the more niche type valves.

In the sanitary process industry we have specified and applied thousands of sanitary pumps into a huge variety of high purity applications in the food, beverage and biopharmaceutical industries.  To identify the best sanitary pump for the application we rely on a number of analytical tools to assist in the process, including several pump sizing programs, pressure drop calculation software, manufacturers data as well as a lot of tribal knowledge we have developed over the years.

A major key in selecting the proper pump is to get as much application data as possible from the client.  Some clients have a vast knowledge of their product and application, others are much more limited, or sometimes not known at the time of request.  To assist in this process we have published a “Pump Application Datasheet” we request customers fill out to the best of their ability.  In this posting we thought we would review the data we ask for on the datasheet, what it means and why it is important.

• Application Description:  Understanding the application gives us a much better feel for what type of pump will do the job. We’re trying to figure out what you want to accomplish. Case in point:  An application for 20gpm @ 30PSI for a liquid transfer from one tank to another may use a very different pump than one at the same flow rate and pressure that is metering a fluid in a filling application.
• Fluid Description:  Different fluids will require different seal and elastomers. Different fluids also have different vapor pressures that can affect the suction conditions of a pump application.
• Viscosity:  Determining the viscosity of the fluid is critical.  Higher viscosity products won’t work with a centrifugal pump.  Extremely high viscosity fluids can create suction issues that need to be address on positive displacement pump applications. Viscosity is also important in calculating friction loss.
• Density/Specific Gravity:  This can affect centrifugal pump sizing criteria as well as horsepower requirements
• Temperature:  Both the process and cleaning temperatures are very important.  In a sanitary rotary PD pump such and a Waukesha Universal pump, higher temperatures may require the pump to have undersized rotors to prevent them from contacting the casing and front cover as the wetted parts of the pump expand under heat.  Temperatures can be a factor in proper elastomer selection.  Also, elevated temperatures affect the vapor pressure of a liquid and consequently the net positive suction head available.
• Flow Rate:  This one is pretty obvious
• Discharge Pressure:  This is critical in sizing centrifugal pumps in particular.  Proper sizing cannot be completed without a discharge pressure requirement.  Discharge pressure can also affect PD pumps in that all PD pumps have a maximum pressure rating.  The pressure also affects horsepower requirements.  If you don’t know you pressure requirement we will help you determine that using the discharge conditions listed further below on the datasheet.
• Is the Product Sticky or Abrasive?  This directly affects the mechanical seal material selection and whether or not a seal flush will be required.
• Suction Conditions:  A general overview of the suction piping can help to specify a pump that meets the net suction pressure. Are you coming out of a tank? How high off of the ground is the tank? Are there any suction flow restrictions?
• Discharge Conditions:  If you don’t know your discharge pressure requirements, give us the discharge conditions, i.e. a brief description of the process, the piping sizes, lengths and elevations.  We can use that data, along with the flow rate and viscosity information to generate your pressure requirements.  We have developed in house software that will do these calculations quickly and accurately.
• Seal Requirements:  If you know you seal requirements, i.e. single or double mechanical seal, seal materials and elastomers, tell us here.  If you need a recommendation we can do that using the fluid properties and temperatures on the upper part of the form.
• Motor Requirements:  There are a lot of choices in motors (see our earlier blog on different ratings and enclosures for motors).   This section allows you to specify your requirements.  If are unsure, we will walk you through the process.

TAG, Centrifugal Pumps, Sanitary PD Rotary Pumps, Sanitary Pumps