Highly sensitive instruments and equipment used in analytical chemistry and medical device applications require extreme capabilities. To provide unique differentiation of their products and meet their customers' challenging requirements, original equipment manufacturers (OEMs) rely on versatile state-of-the-art components.
One such component, the solenoid valve, provides precision control in gas and liquid handling applications. As market demand continues to push for increasing capabilities of these instruments, OEMs encounter the need for fluidic components that also push performance boundaries, such as lower leak rates, higher temperatures, and higher pressures.
This blog presents examples of how a high performance solenoid valve serves as a solution to challenging engineering requirements in critical applications such as gas chromatography and mass spectrometry (GC/MS), laser therapy and home hemodialysis.
Gas chromatography utilizes two physical properties of gases to separate and detect gas concentrations. The first of which is the boiling point. A small sample, often less than 1ml of liquid in size is prepared in a known solvent. The mixture is then presented against the near-vacuum of the flowing column causing the mixture to boil and enter the column (a long tube) in a predictable manner based on the pressure and temperature of the sample. The second property is the compound's mobility within the carrier gas of the flowing column. Compounds with a greater affinity for the carrier gas will reach the other side of the column quicker. At this point, in the case of a regular GC, the compound would reach a detector, be observed and measured. In the case of a GC/MS, the output of the GC is connected to an ionizing chamber of a mass spectrometer.
Mass spectrometry is again based on two physical properties of a compound, in this case, the molecular weight and the charge generated during ionization of the molecules in the compound based on the chosen ionization method. A mass spectrometer uses an electric field to generate or influence the flight of these ionized molecules. Since all molecules are influenced based on the charge that they have, the heavier molecules are affected less by being slower. These molecules are then detected usually by their charge at the end of their flight based on the time it took for them to fly that distance. Thus, this method is called the time of flight or TOF.
Since the basis for mass spectrometry requires the isolation of the molecular weight as a property, it is important that there be no resistive fluid within the chamber. A mass spectrometer must operate in a vacuum; different types of these systems require more severe types of vacuum. A solenoid valve with a very low leak rate, such as Parker's Series 9 Miniature Calibrant Gas Valve may be used to backfill the chamber with inert gas, such as nitrogen, during downtime or maintenance. This is especially important in a time of flight or cryogenic mass spectrometry where vacuums of 1 x 10-8 to 1 x 10-10 torr can be observed. This greatly reduces the pump downtime of a given system so long as nitrogen saturation is maintained between sessions since less vacuum boilable compounds can contaminate the system. A normally open configuration is also used as a safety mechanism in the event of a power failure.
Laser therapy is used to treat everything from cancer to tattoo removal to reducing age-related skin damage. Lasers are used in one of three ways on the human body. They can stimulate repair and growth of human tissue in the case of anti-aging treatments, to focus on specific compounds in the cases of tattoo or hair removal, or for laser ablation therapy in the cases of cancer treatment and removal.
Laser treatment can be uncomfortable or painful, especially where laser ablation is required. That is why some companies have chosen to add the dispensing of refrigerants at the site of treatment as the laser fires. Refrigerants are expensive, have the potential to damage the atmosphere. Consequently, it is important to dispense the correct amount of coolant gas to the site. It is very important as well that no additional refrigerant escapes when the system is not in use. As many refrigerants degrade, small concentrations of corrosive gases begin to appear, posing a shortened lifetime to many materials. Because of its compact size, low weight and extremely low leak rates, the Series 9 valve is ideal in this application to precisely deliver the coolant when the device is in use. The valve can be built directly into the hand-held wand delivering the laser treatment so that the valve is right at the point of dispense and ensures that none of the coolant leaks, whether the unit is in use or not. This reduces the cost to the laser therapy operator and ensures that the patient and environment are minimally impacted using the coolant.
With home hemodialysis, patients can be treated daily in their homes using much simpler, less costly equipment. The result is less patient discomfort and disruption of life. Technical challenges to this method of care are the ability to generate dialysate and dialyze at home. Originally, generating dialysate at home was done in small batches ranging from 5-20 liters. Advanced filtration was used to make sterile de-ionized water, which was then mixed with pre-measured concentrate, and shipped. Since the concentrate involved mixing, then testing, setup time was required prior to treatment
In the last 10 years, a new technology for on-demand dialysate has been introduced where the solution is generated using similar filtration technology and small amounts of the required chemicals are added as the mixture is tested, used and disposed of. The addition of these chemicals to the mixture must be in precise amounts — requiring fast response times and low internal leak. The need for sterility demands stringent external leak, and the corrosive nature of both dialysate and the sterilizing chemicals used to clean the devices after treatment requires corrosion-resistant hardware. The Series 9 is made of 316 stainless steel and has FKM seals to insure corrosive resistance to cleaning chemicals.
The Series 9 valve is a truly versatile product that has been proven to solve extreme engineering design challenges in some of the most innovative analytical and medical devices. Its low leak rate is rivaled by few other products on the market and its unique construction using non-corroding passivated 316 stainless steel and FKM seals render it a great match for aggressive chemicals.
The Series 9 valve can also be offered with analytically clean service or as part of an integrated sub-assembly module. Our expert team of engineers are available for further consultation regarding any required customizations.
Solenoid valves can be designed with a specific application in mind and over time become applicable to other applications due to its high quality and durability. In the Series 9 case, the valve was constructed with extremely low leak rates, high repeatability, non-corroding materials, high pressure and temperature, versatile fittings, orifices seals and voltages. In addition, the valve has the option to be built in a subassembly subsystem and analytically cleaned. All this is packed into a miniature lightweight design. The Series 9 valve is truly an amazing design that will continue to be used in different applications due to its remarkable versatility.
Parker Precision Fluidics has over 30 years of experience in developing valve and pump technologies. Our engineers specialize in helping OEMs update original valves that are producing low yields.
Our applications engineering team is always available to provide recommendations and customize equipment to customer specifications.
To learn more about Precision Fluidics' miniature valves, flow controllers, pumps and accessories, please visit our website, or call 603-595-1500 to speak with an engineer.
Article contributed by Collin Creegan, Valve Customs Engineer III, Precision Fluidics Division, Parker Hannifin.