The Plast-O-Matic Quality Assurance Team turns an angry customer into a satisfied -- and very thankful -- customer.
A leading international semiconductor manufacturer recently cut out and sent a section of pipe to Plast-O-Matic complaining of a leaking check valve, pointing to cracks on both the inlet and outlet. Cracked ports on a new valve generally indicate that the installer used a pipe wrench or channel locks, where only a strap wrench should be used. With tell-tale teeth marks on a nipple, it initially appeared that overtightening was the cause.
In this particular case, inspector Ron Cline found an unusually high number of cracks, not only on the Plast-O-Matic check valve, but also on other valves and fittings in the pipe section. Ron turned his findings over to Greg Michalchuk, Plast-O-Matic's Quality Assurance Manager, who immediately discounted excessive elbow grease:
"If a crack develops in a PVC part due to radial stress, the crack widens under load, but usually no additional cracks develop," Greg explains. If an additional crack were to develop, it would most certainly not form within such close proximity to the others.
A liberal amount of thread sealant was cause for suspicion. At this point, Plast-O-Matic Vice President-Sales Bob Sinclair and Technical Sales Manager Andy Ryan got involved and called our regional representative, Jim Pringle, to investigate further. The customer explained that the contractor was using Swak® anaerobic thread sealant throughout the piping system. A call was made to Swagelok Corp. to obtain a Material Safety Data Sheet, known as an MSDS.
Two ingredients in Swak® were immediate suspects: A dimethylacrylate (30 - 40%) and Propylene Glycol Azelate (20 - 30%). A spokesperson from Swagelok immediately confirmed that Swak® is an excellent sealant for stainless steel piping, but incompatible with PVC!
The customer had many of these subassemblies in-line, and in a semiconductor fab the potential loss was staggering. Proper installation techniques were used for the rest of the job, and the parts installed using the incompatible sealant were replaced prior to certain failure.
Because of Plast-O-Matic's team effort to find the true cause of the problem, an angry customer was turned into a thankful one.
Vacuum Breaker Solves IBC Leak Problem
.... Beneficial for All Types of Storage Tanks
Cedar Grove, New Jersey USA & London, England -- Intermediate Bulk Storage Containers (IBC's) are commonly used in Europe to transport chemicals to companies which have minimal on-site requirements. Vacuum breakers are used on the tanks to prevent implosion during drainage, yet must not allow fumes to escape from the tank.
A leading U.K. manufacturer of 1000 litre IBC's was experiencing problems with a spring-operated vacuum breaker. The spring design did not provide an effective seal and permitted fugitive emissions. The problem was most significant during transport, when sudden motion resulted in severe product leakage. Because the IBC manufacturer's largest customer was primarily shipping a solution of 36% hydrochloric acid, the situation was critical.
The company tested a number of vacuum breakers, but was unsatisfied until finding a U.S. manufactured product from Plast-O-Matic Valves, Inc., based in Cedar Grove, New Jersey. The Plast-O-Matic True-Blue Vacuum Breaker, with a one-of-a-kind elastomeric diaphragm, was the only corrosion-resistant device able to meet the design criteria: Prevent tank implosion, yet remain sealed in all other situations regardless of motion or mounting position.
Patented Diaphragm
The diaphragm in the Plast-O-Matic True Blue vacuum breaker creates a bubble-tight seal, and sealing is unaffected by motion or direction. Installation at the highest location in a tank is recommended. After breaking a vacuum, the patented design causes the diaphragm to reposition and close in an identical location - a quality known as "positive repetitive sealing" - which means that it will prevent emissions and leaks throughout the life of the IBC.
To maintain the bubble-tight seal, the True-Blue Vacuum Breaker requires a minimum vacuum of at least 2" Mercury (1 PSI) to open, which is well within the maximum negative pressure of 10" of Mercury for an IBC. The flow rate of the vacuum breaker at 10" of Mercury is 50 cubic feet of air per minute. For tanks that can withstand 20" of Mercury, the flow rate is 95 cubic feet of air per minute. The breakers are manufactured in PVC, Polypropylene, Kynar® (PVDF) or PTFE and fulfill the need for corrosion resistance in chemical IBCs.
After reviewing case histories of the True Blue vacuum breaker in other tank applications, the IBC manufacturer tested and soon specified it into the product line. Since the switch, the emissions and leaks have been eliminated.
Useful in Many Tank Applications
Plast-O-Matic's vacuum breakers are designed to protect many different types of tanks and storage vessels from collapse or structural damage during draining or pumping, as well as to prevent liquids from siphoning back into a tank. In one popular tank design, the breaker prevents liner separation; please click here for an application diagram in .pdf format. It is also used in large underground storage systems, where the True-Blue Vacuum Breaker is installed in an above-ground housing and connected to the tank or cavity via piping. The breaker is surprisingly compact, in pipe sizes from 1/2" to 1" NPT with total height ranging from 4.3" to 5.1". Maximum working pressure is 6,9 bar @ 24ºC (100 PSI @ 75ºF).
A special cap protects the Plast-O-Matic vacuum breaker by preventing foreign matter from entering the valve. It is also designed to minimize the "whistling" commonly associated with these devices. But for tank manufacturers and system designers - who know that vacuum conditions can wreak havoc - a little whistling is music to the ear!
* * * * * * * *
In addition to vacuum breakers, typical Plast-O-Matic products associated with tanks and storage systems include check valves, relief valves, by-pass valves, gauge guards, level indicators and sight glasses.
Sight Glasses Provide Leak Monitoring
in Dual Containment Piping System... Beneficial for Liquid & Gas Pipelines
Cedar Grove, New Jersey & Odessa, Texas -- To satisfy a need for visual monitoring of leakage in dual containment systems, a petroleum plant has installed a series of Plast-O-Matic's "sight glasses" in its diesel fuel piping. The devices, which are simpler and less expensive than other monitoring methods, provide instant visual confirmation of a leak in the primary pipeline.
The Sight Glasses are installed on 1/2" connections at key points in the bottom of the outer containment pipe. In the event of a leak, the fuel will collect at the lowest point--the sight glass--and raise a day-glo float in the chamber. As the brightly colored float rises above a blackened portion of the sight glass, it creates instantly recognizable visual confirmation of the problem.
Constructed of corrosion-resistant Pyrex® on the inside wall and high-impact acrylic on the outside, the Plast-O-Matic sight glass meets the need for for dual containment throughout the system. O-rings allow the indicators to seal at low pressure as well as high pressure, an attractive feature for dual containment systems. A full 360° viewing area in the sight glass permits inspection from anywhere near the piping.
Please click here for an illustrated technical diagram of this application in .pdf format.
Useful in Many Applications
Plast-O-Matic's sight glasses are designed to give instantaneous visual confirmation of pipeline flow. In another application, the sight glass is installed directly in a soil remediation system, where streamers within the chamber flutter when flow is present -- please click here to view an illustrated technical diagram of the soil extraction application in .pdf format. It is also frequently used to visually confirm the presence of a process additive; in these cases the sight glass is installed downstream of an injection system. The sight glass is surprisingly rugged, and is available in pipe sizes from 1/2" to 8" NPT. Standard O-ring seals are of Viton or Buna-N.
The sight glasses, from Plast-O-Matic's True-Blue line, are manufactured with PVC, Corzan® CPVC, Polypropylene, Kynar® PVDF or PTFE ends. Please click here for complete details.
CKS Replaces Ball Check in RO Water System A flexible circuit manufacturer in Chandler, Arizona was having a problem with backflow from a large reverse osmosis water storage tank.
In this application, water is fed from a degassifier (removes air bubbles) into a 1 hp, 30-50 GPM pump. The pump is used to push the RO water approximately 30 feet up a 2" vertical pipeline into a large storage tank. To prevent backflow and siphoning when the pump was off, a check valve was installed 8 feet high on the vertical pipeline.
Unfortunately, a ball-type check valve was specified. According to Joe Ujvari, Ryan Herco, Tempe, "The typical ball check would never create a positive seal on the vertical column up to the top of the storage tank". He explains that the lack of a positive seal would cause water to back up and flood the reservoir coming out of the degassifier.
When the electronics firm called Joe in to troubleshoot the system, he turned to Plast-O-Matic's Series CKS Check Valve. Designed with a special PFA encapsulated spring (not a "coated" spring), the CKS provides a bubble-tight seal without compromising the ultrapure requirements of the application. Unlike ball-type check valves, the CKS does not require backflow to close. It automatically seals bubble-tight in the absense of inlet pressure - no backpressure is required.
by Mike Johnson, Harrington Industrial Plastics, Jacksonville
Water Utility Problems Solved in Florida The Jacksonville Electric Authority provides electric, water, and sewer utility services. The city uses sodium hypochlorite in lieu of traditional gas chlorination to disinfect the water supply.
In several applications, they use a brine solution to generate their own sodium hypochlorite. This generator process involves mixing sea salt with soft water to create a brine solution, which is then electrolyzed and produces a dilute chlorine solution.
The original construction used common metal solenoid valves for the soft water make-up lines to the fiberglass brine tanks. After just six months of operation, one badly corroded metal valve stuck in the energized open position which caused a tank overflow.
When the plant maintenance crew called Harrington Industrial Plastics for help, we recommended Plast-O-Matic non-metallic EASMT direct acting solenoid valves to solve the problem. They have since replaced the water make up valves on all four tanks with Plast-O-Matic.
While working in the plant we were approached with another challenge. They had PVC ball check valves in a horizontal line of diluted brine solution which would not check when the line depressurized. Due to the close tolerances of the piping system, it would prove difficult to re-install another type check valve in the same position without doing substantial re-piping. Enter the Plast-O-Matic Series CKM. Because of the CKM's unique design, it could be installed downstream in a vertical, north to south flow orientation and still provide reliable checking. The original check valve was left in position (minus the ball) and the newly installed Plast-O-Matic check valve is working great! The CKM was soon retrofitted on each of the generator skids.
Jacksonville also installed numerous GGMT Gauge Guards on filtration units added during the plant upgrade. Plant maintenance then replaced several corroded gauges with Plast-O-Matic GGMT's and added RVDT backpressure regulators at the feed pump.
Schedule 40/Schedule 80 Comparison
Tested at 73° F: Sch. 40 Sch. 80 % difference Max. Working Pressure 300 PSI 470 PSI 42 % Short-Term Collapse Pressure 356 PSI 927 PSI 160 % Resistance to Load
(uncompacted soil)1084 lb/ft 2809 lb/ft 159 % Wall Thickness .145" .200" 38 %
This chart is only a general guideline, based on laboratory conditions. In real applications, systems vibrate, UV rays affect performace, temperature fluctuates....these and a myriad of other everyday conditions will adversely affect plastic piping.
As temperatures rise, the plastic softens. As temperatures decrease, plastic becomes brittle. Ultravilot rays (sunlight) slowly degrade the molecular structure of most plastics. Vibrations create inherent stresses, which can lead to cracking.
UV Stabilized Valves
PVC and polypropylene valves are highly weather resistant, but will become oxidized after extended exposure to ultra-violet light. UV rays affect valves by degrading the molecular structure of the polymer.
The degree of oxidation is dependent on the level and intensity of exposure: In sunlight, oxidation can take a number of years and will result in discoloration and embrittlement. This does not affect performance or pressure capacity - so you may not have a problem - but it does make the valve vulnerable to impact damage.
When a PVC or polypropylene valve is connected to a UV sterilizer, the level of exposure is much greater and the thermoplastic is eventually prone to stress cracking. For UV sterilizers, PVDF is generally the valve material of choice and is not subject to the same type of degradation.
In outdoor applications, heavily pigmented common latex paint will inhibit the damage from sunlight. In some situations, however, painting may not be practical. In polypropylene applications, paint does not properly adhere to the thermoplastic. PVDF may not be cost-effective or desired in certain applications either.
Plast-0-Matic now offers UV-Resistant thermoplastics as an optional valve material for applications exposed to UV where paint or PVDF is not practical. Manufactured from Grade 1, Type 1 PVC or polypropylene with added carbon black, these valves generally withstand UV exposure with less oxidation and molecular degradation.
The added carbon black effectively blocks the UV component, and allows the valve to maintain its properties, even in installations with high UV exposure.
UV-resistant PVC or polypropylene eliminates the need for paint and other costly maintenance techniques, yet costs only slightly more than standard resins.
The UV-Resistant feature is available on most popular Plast-O-Matic valves up to 2" pipe sizes. Minimum quantities apply and these materials may not be practical in every situation with UV exposure. To determine the best solution for your specific application, contact our Technical Sales Team in Cedar Grove at 973-256-3000.
Case History: Pilot Solenoid Valves at Bremerton Public Works
The City of Bremerton, Washington needed to build a system to bring its pH levels in line with the Lead and Copper laws, with the flexibility to compensate for a variety of water sources.
Dealing with pH levels below neutral, the Engineering Division of Bremerton Public Works and Utilities had to provide a system for injecting caustic soda into the water main. "We deal with a number of different sources," explains Tom Knuckey, head engineer, "a few surface water sources, supplemented by some wells, so the pH varies."
To compensate for the fluctuation, a pair of 4,000 gallon tanks with a series of metering pumps and analyzers allow the caustic soda to be diluted when the water supply is closer to neutral. "It may start at full strength, then go to 50% strength, 25%...whatever is needed," explains Knuckey.
The system design called for precise dosing into the pipeline from a pair of valves controlled by pH sensors upstream and downstream of the treatment point. The 30 PSI backpressure created by the city water main was a primary concern. The valves specified would have to open and close accurately against the high backpressure, and resist corrosion from the sodium hydroxide.
Overcoming the corrosion problem was relatively simple; thermoplastics would provide significantly better performance than metals. Of the common plastic valve materials, polyvinylchloride (PVC) was selected for its compatibility and relatively low cost. At that point, the possibilities covered a wide range of valve styles and actuation package combinations.
For speed and dosing accuracy, solenoid valves were the most likely candidates. The main pipeline, however, posed a problem since most standard 1" pipe size PVC solenoid valves cannot actuate against 30 PSI backpressure and deliver a high flow rate.
While searching for a solution, Bremerton Public Works contacted Plast-O-Matic Valves, Inc. of Cedar Grove, New Jersey. Plast-O-Matic, one of the longest established plastic valve manufacturers, suggested a solenoid valve with a "pilot" orifice. Known commonly as a "pilot-operated" solenoid valve, it uses a standard sized coil to first open and close against a small amount of flow. The line pressure, in turn, is used to actuate a much larger main orifice. The pilot design is slightly slower than a direct-acting solenoid valve, but is able to provide excellent flow capacity with relatively high pressure. The split-second hesitation inherent to the pilot provides the added benefit of virtually eliminating the water hammer that an instantaneous solenoid valve might cause.
The valve specified, Series PS from Plast-O-Matic, offers flow capacity from 5.2 Cv to 80 Cv depending on size. The design provides an inlet pressure rating to 140 PSI and backpressure to 70 PSI. A pressure differential of 5 PSI is required for the valve to operate properly. In the Bremerton installation, a 1" valve was specified, which provides a Cv of 9.5. The Series PS also offers a number of appealling safety features to the public works team. It provides a patented "Fail-Dry" safety vent, which allows the valve to continue operation in the event of a primary seal failure. The PS also has a PTFE bellows dynamic seal, offering the ultimate protection against fugitive emissions.
To further enhance the accuracy of the system, Knuckey's crew also specified a corrosion-resistant backpressure/relief valve from Plast-O-Matic. Known as the Series RVDT, these valves provide a constant backpressure on the discharge of the caustic soda metering pumps. This allows for a repeatable, constant fluid discharge per stroke, and enhances the system accuracy.
According to Bill Davis, P.E., who worked with Plast-O-Matic to specify the valves, the pH treatment facilities went online during second quarter 1999. The water system is designed to provide six million gallons per day.
Naturally, Plast-O-Matic Technical Sales is always glad to assist you with any questions concerning pressure, flow or other issues.
You can contact Technical Sales at (973) 256-3000 or E-mail us at info@plastomatic.com
Plast-O-Matic Valves, Inc.
1384 Pompton Avenue
Cedar Grove, NJ 07009 USA
Voice: (973) 256-3000
Fax: (973) 256-4745
Top of Page
KynarŽ is a registered trademark of Arkema. Copyright© 1998-2008 Plast-O-Matic Valves, Inc.
CorzanŽ is a registered trademark of Noveon. VitonŽ is a registered trademark of DuPont Dow Elastomers.
