Dave Nordling, Secretary, Reaction Research Society
The RRS held its monthly meeting on Friday, June 14, 2019, at the Ken Nakaoka Community Center in Gardena, CA. We had several discussion topics on the agenda, but we had a last minute confirmation of a special guest. Terry Price, a nationally recognized expert in composite materials, gave the society an overview of composites used in many industries including aerospace.
Terry’s presentation lasted for nearly the entire meeting, but no one seemed to mind. It’s a fascinating subject with many applications. Those specific to rocketry would be composite over-wrapped pressure vessels and tubular composite air-frames.
Another one of our guests at the meeting was Dennis Lord who is president of the Experimental Aircraft Association, Chapter 96 (EAA 96). Dennis came to help promote the EAA and let us know that the National Transportation Safety Board (NTSB) was going to make a presentation at their meeting on Saturday, June 15th. The EAA meets every 3rd Saturday of each month.
At the very end of the meeting, Osvaldo did bring up a few topics, mainly about the past Mojave Test Area event we had with UCLA on June 1st, and the next event we’re planning with LAPD CSP on July 13th. The RRS has had some issues with the MTA site being left untidy by our guests. The RRS would like to remind our visitors to please pick up their trash before they depart.
Also, the use of male anchor bolts, which are commonly available at hardware stores like Home Depot, while convenient to the builder make for a terrible tripping hazard as these bolts remain planted for years. As we are getting more users at the MTA site, the number of irregular protruding bolts is growing and becoming irksome. The best solution is to work with the RRS before making changes to our concrete and using female anchor bolts which may require ordering in advance. The RRS has discussed making a common ground interface for all users to adapt their horizontal thrust stands. Although some of our past users may have to redrill their bolt patterns in their equipment, in the long run, it will be simpler and better for all. There will be more on this subject in the coming months as the RRS is pursuing several renovation projects to improve the MTA.
Frank Miuccio spoke about the latest class with LAPD CSP called Operation Progress with the students of Watts. The first classes started in June and the class will finish with the launch event at the MTA on July 13th.
One of the last topics before we adjourned late on that evening was a new payload being made by returning RRS member, John Krell. Nearly all of our RRS standard alphas, flown by the dozens several times a year, fly with empty payload tubes. There has been much conjecture on the apogee height and burnout velocity of an RRS standard alpha micrograin rocket. Best estimates are that they are subsonic and may be reaching heights of nearly one mile. To answer these questions, a simple payload to measure barometric pressure and record the acceleration of the swift alpha.
John’s prototype is only at the breadboard stage, but he has identified the right parts for the first flight prototype using an Arduino Nano microprocessor and a 100G rated accelerometer as best estimates of the RRS alpha acceleration are at least 50G’s.
Our next meeting will be July 12, 2019. We will discuss the topics we couldn’t cover this month including the RRS liquid rocket projects and the RRS social media improvements including adding a better calendar feature for the growing number of events we’re having.
Our next launch event at the MTA will be July 13th with the LAPD CSP.
David Escobar, Director of Engineering at Metso Automation
Industrial oxygen is used for many purposes: in a basic oxygen furnace for making steel, water pollution countermeasures, including sewage treatment, habitability and superfund site rehabilitation, and chemical processes such as production of vinyl chloride, nitric acid, epoxyethane and hydrogen peroxide. It is also used for medical treatment, life support in harsh environments and industrial gasses for welding and other processes.
The production of oxygen has risen from approximately 470 billion cubic feet in 1991 to over 1.5 trillion cubic feet in the U.S. and more than 4 trillion cubic feet globally in 2014.
Oxygen is the most common oxidizing gas and is, of course, highly reactive. When dealing with an oxygen-enriched environment, it is important to control the sources of ignition. Ignition can be caused by many things, among them:
Electrical arcs, which can come from electrical equipment or even static discharge
Friction, which can be generated by the sliding contact of materials within the oxygen-enriched environment
Impact of particles or projectiles internal or external to the enriched environment can generate heat
Resonance, which is vibration-induced heating
Heat of compression (HoC) is the most common cause of explosion due to contamination. Heating is caused by the adiabatic compression of a fluid; this is often called auto-ignition.
Auto-ignition is the phenomenon of spontaneous ignition of a fuel source due to the heat generated by the sudden compression of a gas or HoC. When a valve in a high-pressure or high-velocity oxygen flow is opened or closed quickly, the kinetic energy is converted to increased temperature and potential energy in the form of increased pressure. If the temperature generated by the compression exceeds the temperature needed to ignite non-metallic seals or even the pipe itself, the result is a spontaneously explosion or auto-ignition. When this happens in oxygen systems, the effect can be devastating.
Because the HoC is substantial and can generate thousands of degrees of temperature even at moderate pressure ratios, oxygen systems are designed to limit the pressure drops to control HoC and limit temperature within the autoignition temperatures of the system components.
Thus, it is absolutely essential that contaminants, which can introduce lower auto-ignition temperatures than even the non-metallic seats and seals, be removed from any oxygen system. Any method that achieves the desired cleanliness level is acceptable. CGA 4.4 and the recently issued MSS-SP-138 provide excellent recommendations for cleaning processes.
CONTAMINANTS TO BE REMOVED
Basically, anything that promotes combustion or impact product purity is considered a contaminant. ASTM G93 categorizes contaminants into three types:
Volatile Organic Compounds (VOC)
Hydrocarbon-based greases and oils
Water-based detergents and cutting oils
Particles, lint and fibers
Dust – Weld slag, etc.
Specifications vary on cleanliness level, methods and validation, and include how much residue is acceptable, what method of cleaning can be used and what kind of inspection must be conducted.
Mechanical cleaning is used to remove scale, coatings, paint, weld slag and other solid contaminants and can include grit or ice blasting, wire brushing and grinding.
Aqueous cleaning can be with hot water and steam cleaning or alkaline cleaning. Hot water and steam cleaning is effective against water-soluble contaminants, and is normally used with detergent. Alkaline cleaning uses caustic salt in water to create a highly alkaline solution. It is effective against hydrocarbon oils, grease and waxes, and generally is enhanced by agitation and/or jet spraying. Typically this is used for industrial parts washers. This process is greatly enhanced by ultrasonic agitation, but the solvent residue must be removed as well.
Semi-aqueous cleaning uses hydrocarbon solvent and water emulsion, which is effective for removing heavy contaminants from parts like heavy grease wax or hard to remove soils. Emulsion may require agitation to maintain the mixture, and parts must be rinsed before the emulsion can dry. Otherwise, contaminants may re-deposit on the part that was cleaned.
Acid cleaning varies substantially based on the acid used.
Hydrochloric acid is used to remove scale, rust and oxides. and to strip platings (chrome, zinc, cadmium, etc.) and other coatings
Chromic and nitric acid are used to for passivating, deoxidizing, brightening and removing alkaline residues in addition to cutting oils
Phosphoric removes oxides, light rust and fluxes
Acids must be removed completely from the part prior to drying and, depending on the acid strength, may need a neutralizing process.
Solvents can be used without water dilution or emulsion. Alcohol is a common solvent often used to revisit areas of concern identified by black (UV) light inspection. Solvents like alcohol evaporate completely, leaving no residue.
Vapor degreasing is a process in which a solvent is heated until it vaporizes, while the part is maintained at a lower temperature. The solvent then condenses and dissolves contaminants. The part must be oriented so that the condensed solvent can drain from the part by gravity. This method is very effective for inaccessible areas on parts but requires a contained environment for the part during the process.
Any combination of cleaning methods that achieve the desired cleanliness level is acceptable.
Visual inspection can be direct, including white light, which is effective in detecting contamination down to 500 mg per square meter. UV (black) light visual inspection identifies contaminants that fluoresce and is effective in detecting contamination down to 40 mg per square meter.
Indirect visual inspection is done in two ways: wipe test and solvent filtering. A wipe test can identify contaminants in locations that have no direct line of sight. Typically, both white light and UV light are used on the wipe cloth, and are effective in detecting contamination down to 30 mg per square meter. Solvent filtering rinses the inaccessible area in solvent, which is then filtered to capture contaminants. The filter is then visually inspected and can detect 100 ml per square foot of low residue solvent and it also uses white and UV light.
Quantitative inspection is done by evaporating the solvent used for cleaning and obtaining the weight of the remaining effluent. Acceptable levels of residue vary according to user requirements.
Clean room: This provides a designated location where the environment limits dust airborne particles, where clean tools and clean assembly and test equipment can be stored. It can also provide controlled lighting for visual inspections.
Clean test equipment: Pressure test equipment contains contaminants in hoses and pumps. If a test machine cannot be dedicated for clean testing, give special consideration to cleaning of test equipment or alternate testing with clean gas.
Packaging: After cleaning, give specific instructions on how to package the product to preserve cleanliness in shipping and subsequent storage. Consider the role of desiccant as a possible contaminant. Use compatible products or control desiccant to prevent contamination. Consider the addition of actuation and accessories to the valve. Can the actuator be installed and set up without violating the protection? If the protection is compromised, are there procedural steps to identify and remediate any contamination?
Oxygen cleaning is used to remove contaminants that can significantly reduce the temperature of auto-ignition. There are many methods for doing the actual cleaning. CGA 4.4 and the recently issued MSS-SP-138 provide excellent recommendations, but any method that achieves the desired cleanliness level is acceptable. It is important to know what level of cleanliness your standard process produces. Process validation using a quantitative measurement allows the supplier to have confidence in process quality when using qualitative inspections for production work.
Editor’s Note: The following article was posted on April 20, 2015 in Valve Magazine.com. It is reprinted here for the Reaction Research Society (RRS) with permission from the author and Valve Magazine. The information here is very useful in amateur rocketry and is intended to make our readers aware of the importance of a proper oxygen cleaning process for lines and valves. High purity oxidizers must be handled with care and cleanliness is of paramount importance. The RRS would like to thank David Escobar of Metso Automation and Judy Tibbs, Director of Education at the Valve Manufacturers Association and Editor in Chief of VALVE Magazine.
CGA refers to the Compressed Gas Association. Founded in 1913, the CGA is an organization dedicated to the development and promotion of safety standards in the industrial, medical and food industry. The CGA is comprised of over 110 member companies worldwide working together through the committee system to create technical specifications, safety standards and educational materials; to cooperate with governmental agencies in formulating responsible regulations and standards; and to promote compliance with these regulations and standards in the workplace.
For more information, go to the CGA website:
MSS refers to the Manufacturers Standardization Society of the Valve and Fittings Industry. Standard practices (SP) documents are available related to many applications including the standardized practice of oxygen cleaning (ANSI/MSS SP-138). ANSI or the American National Standards Institute has adopted the standard for oxygen cleaning of valves and fittings.
ASTM stands for the American Society for Testing and Materials. It is now an international organization known simply as “ASTM International” with its headquarters in West Conshohocken, Pennsylvania. ASTM publishes voluntary consensus technical standards including ASTM G-93 for the Standard Practice for Cleaning Methods and Cleanliness Levels for Material and Equipment Used in Oxygen-Enriched Environments.
For more information, go to the ASTM International website:
by Larry Hoffing, Educational Outreach Coordinator, Reaction Research Society
The Reaction Research Society (RRS.ORG) is glad to be a part of an upcoming event with Spaceport L.A. The “Rocket Workshop with the RRS” is an excellent opportunity for anyone who wants to get directly acquainted with rocketry. This event is meant for both professionals and non-professionals alike. From younger students to university students of all fields, to adults, this event is meant to give people the experience of assembling and flying your own rocket.
The event will begin on Saturday, May 4, 2019 with a subsequent launch of the rockets from the RRS Mojave Test Area (MTA) on Saturday, May 18, 2019. At this event, you can learn about the fundamentals and more practical knowledge of rocketry.
The event will be held at the HexLab MakerSpace in Van Nuys. This is laser-cutting service in the Los Angeles area. Check the Spaceport L.A. website for the details and updates.
The RRS standard alpha rocket is a very old, but reliable design still used in the society. Although micrograin propellant is not used anywhere else but at the RRS (where it was initially discovered in the 1940’s), it is a simple and powerful propellant combination that makes for an impressive show of raw power. I have attached an earlier description of the RRS standard alpha rocket below.
After the first session, on the second event, you can go out to the RRS’s private Mojave Test Area (MTA) at Koehn Dry Lake, east of Cantil, California in the high desert. The RRS will handle the propellants, you can see the impressive results from the safety of our observation bunker.
Amateur rocketry is our passion and purpose and the society is glad to hold this event with Spaceport L.A. and the public.