With legalization comes regulation, and a current one is that the extraction equipment and the operating system that it is installed in, must meet ASME, IFC, IBC, IEC, and NFPA-58.
Prior to that time I had the central Mk III, IV, and V Terpenators certified to ASME using R. Chilton, ME PE, primarily for liability and liability insurance reasons. ASME Section VIII designates any piping 6" and under as Pressure Piping, and LPG pressure piping must be capable of 350 PSI.
Larger that 6" and under more than one atmosphere (14.7 psi) pressure, is designated as a pressure vessel, which must withstand a minimum of 3X its maximum operating pressure, as well as have a suitable PRV or rupture disc.
After regulation requiring certification of the overall systems, I used Pressure Safety Inspectors, LLC (PSI) to certify the Mk IVC and VC, which was by far the most complex and involved to certify.
SN00012 Mk VB that WolfWurx previously built for a client in the idyllic Lake Chelan region in the misty land of WA, was subsequently certified along with the extraction room that it was in, to meet Measure 502 by Kirkland Dynamics, after removing the silicone mat heating pads. For the C model Mk's, we used hot water for that purpose, supplied from outside the NEMA 7, Class 1, Div II room.
Mk IVC SN00013 was the unit that WolfWurx built to the C configuration, and inspected by PSI, before certifying the overall system to meet the requirements in OR, WA, CO, NV, and MD. Mk VC SNPG0014 was the one built by Pharmgold, and the only other ever built in "C" configuration.
As I was again retiring and the C configuration was intended to be my swan song, it was the Alice's restaurant of Terpenators, in that you could anything you wanted, if you just told the nice lady what you wanted.
They were also NEMA 7, Class I, Div I machines, with no electrical in the extraction booth beyond milli-V/A from thermocouple leads.
When I presented SN00013 for certification, I expected a slam dunk, but alas additional steps were required. For starters I wasn't expecting the requirement that the collection tank have an ASME placard affixed, so removed the ASME BPE 12" X 12" welded bottom collection vessel and built two variations.
The first was to replace it with a stainless Binks 2 1/2 gallon paint pressure pot, and the second was to have a pressure vessel built by a certified ASME Section VIII tank builder, which I also did, using Marks Brothers.
I had to replace my carbon filled PTFE hoses, with like hoses from Detroit Flex, whom supplied a letter certifying that they met UL-21.
An surprise and education, is that I had to replace all of my stainless heat exchangers, because ASME requires a .049 minimum wall thickness for 1/2" tubing used in LPG application, and 1/2" 304SS is normally supplied in .035 wall, which is what all of our heat exchangers were made from.
Besides having to replace the heat exchangers, I had to have Albina Tubing roll new heat exchanger coils, because the added wall thickness made the tubing stiff enough that I couldn't simply roll them around a mandrel by hand.
The bigger challenge was the counter flow heat exchanger, which no one seemed to offer in .049 wall, so I had those wound by Albina tubing as well. I finished them off with Swagelok reducing tees, and they performed well.
I also had to add more pressure relief valves, and change the LPG tank connections, so that they couldn't bee hooked up backwards.
One of the pressure relief valves was on the upstream side of the 4:1 ratio Haskel pneumatic intensifier recovery pump, and prevented more than 75 psi pressure being applied, so that the pump can't put more than 300 psi on the 400 psi storage tank.
One of the others added was in the line between the tank and flood valve, so that if the line were flooded and both the tank and flood valve were closed, there is relief to hydraulic pressure from expansion, so it can't rupture the 3300 psi tubing.
The second one was in the sight glass circuit, because it also could be flooded and isolated on both side by valves. In this case the 150S John C Earnst sight glasses are only rated at 731 psi, so even more vulnerable.
I had to replace the two 6" 300 psi 13MHP high pressure clamps on the cyclonic filter drier, with LJ Star SSH clamps rated at 725 psi.
Lastly I added more don't do that or touch this, and beware of that labels, covering everything from shock to freeze hazards, as well as some stupidity hazards.
Peer review was a good experience for me, it was a lot of work digging up prints, certifications, and cut sheets for all the components, especially on something as complex as the Mk IVC/VC Terpenators. I had some inkling of that point from having to jump through all those hoops on just the ASME certs for the Mk III/IV/V, but this was easily multiples of ten time more involved.
It cost about $10K to certify the WolfWurx Mk IVC/VC's for OR, WA, CO, NV, and MD.
Something to note, and that is that the PE and fire professionals must also sign off on the way the equipment is being employed, which not only requires a well documented operating manual, but it requires a process that he can sign off on.
The WolfWurx Terpenator process starts off with a pressure and vacuum integrity test, and at the end back fills with N2, so that when the system is opened, it is below 10% LEL. It also uses hot water to bake out the columns while under vacuum, so that they too are under 10% LEL when subsequently opened.
The pneumatic venturi high vacuum pump discharges directly to the exhaust system instead of into the room.
The hot water heaters, the process chiller, the air compressor, and the PID controls are all in an adjacent room, so that there is no electrical in the extraction booth.
The extraction room itself was NEMA 7, Class I, Div II, switching the fan to high volume when the hydrocarbon detector reached alarm state.
The zen of certification is that it requires that the equipment, process and the extraction facility all meet certification standards, but ultimately operating it as specified by the manufacturer lies with the operators. Deviating outside the certified operating standards negates the certification, and ostensibly the liability insurance.
My last point is that without certification, obtaining liability insurance is problematic, so lack of certification is a flag to check if they do have liability insurance to cover any mishaps.