Allow me to take a short trip down the memory lane first.
There was a time when I was a taxi driver. For a brief period. To be more precise - an illegal taxi driver in the collapsing Soviet Union. A Yellow Zhiguli 2102 was my car of choice, the fruit of VAZ factory, which offered unforgettable ownership experience because you had to be a mechanic to be able to drive one of these for more than a couple of hours. That's how I learned basic mechanics, by the way.
I bought a transmitter from an old ambulance, a magnetic taxi roof sign, signed up at a "taxi" firm, and began "taxying" - as simple as that - no paperwork, no licensing - nothing (as long as I wasn't caught by the fiscal police) - that's how things worked back then... So I would go to college during the day, and drive the cab during the night. Good times!
7-8 was my call-sign, and I still remember: "7-8 to base" - "Go ahead 7-8" - "Good evening, Base, Upper center, please" - "Roger that, 7-8, good evening, upper center, you're number 9"...
And I remember that we had these codes, that only us, drivers on the frequency would understand, like for example the code word to transmit in case of a robbery. So when a (presumably stoned) client would inadvertently hear the radio, he'd often say something like - "That's something else, dude... Do you understand all of this gibberish?... Dude... You're like... like cops, dude... Like, in the movies, dude..."
And you know what - very often I see the same thing in hydraulics. (All except for the "stoned" part, of course) We use tons of abbreviations, yet often even us, hydraulic professionals, don't know what the letters stand for, which is why I think it's interesting to "decipher" at least some of them.
Please note two things - I work in Portugal and use terms that are most commonly used around here, which in your part of the Earth may be different, and, of course - since most abbreviations are English, they're more obvious and much easier to remember for native English speakers, so please, don't be tempted to say something like "Even babies know this around here!"
Let's start with hydraulic connections then:
JIC - stands for Joint Industry Council. This is a common abbreviation, and if you look it up, you will see that many establishments in the world adopted some variation of this name. From what I found, the "JIC that matters", responsible for defining the standard for our beloved fittings does not exist anymore. Still - the name remained.
Fun fact - In Portugal JIC is pronounced as "dzheek" as opposed to "jay-eye-see". They're 37-degree flare fittings and are a "looser and cheaper" version of the AN fitting, which stands for Army and Navy, and which you will most likely never use or even see in "normal" industrial applications.
Let's do some metric fittings now, Europe loves them. Around here everyone knows that they come in L and S types, but no one can tell why. Well - it's not "light" and "strong" - it is from German "Leicht" and "Schwer" which means "light" and "heavy". In fact - DKOL and DKOS mean "Dicht Kegel O Ring Leicht" (Tight Cone O Ring Lightweight) and "Dicht Kegel O Ring Schwer" (Tight Cone O Ring Heavy). I am not sure where the "tight cone" came from, but it's 24º included angle, so it might be considered as "tight", I guess. But then they call the 60º metric fitting a DKM which stands for Dicht Kegel Metric, and means "tight cone" as well, for some reason...
BSP - is British Standard Pipe, which can come as BSPP (Parallel) or BSPT (Taper). The most common thread in plumbing and pipe fitting (everywhere except in the US, where they like NPT more). BSP hydraulic fittings use a 60º cone to seal. The external diameter of a male BSP thread will be 1/4-ish of an inch bigger than what its name says (at least for sizes up to two inches) So, a thread that is approximately 1.1/4 of an inch in diameter is actually the 1'' thread. BSP is often written down as G, which came from the respective ISO standard. Why G? Some say that it is because the pipes originally were mostly used for Gas installations, which is why BSP threads are often referred to as Gas threads. Others say this is because the letter G stands for the German word Gewinds, which, means "thread". How original!
The BSP is AKA (Also Known As) - BSF (British Standard Fitting), BSPM (British Standard Pipe Mechanical), BSPS (British Standard Pipe Straight).
Also - sometimes you find BSP threads noted with the letter R. These are (or at least should be) BSPT threads (tapered). R comes from German Rohr - which means "pipe". Not confusing at all, is it?
JIS - Japanese Industrial Standard. Japanese like to be different. They mix everything with everything. Their fittings look like JIC (the ones with the female cone inside the swivel), but use BSP thread and 60º. They look like BSP (the ones with the male cone in the swivel nut), but they're too long for normal BSP fittings. Like I said - different!
ORFS - O-Ring Face Seal, which is pretty self-explanatory, I guess.
NPT - National Pipe Taper. Very often you'd also get NPTF, which is National Pipe Taper Fuel and has, supposedly, a thread form that ensures better sealing. In real life these are interchangeable - you'll use a Teflon filler anyway. Although NPT looks like BSPT - they are different threads. Due to the form of the thread (60º for NPT vs 55º for the BSPT), the TPI (here's another one for you - Threads Per Inch) and a small difference in the OD (Outside Diameter) - mixing these two is a big no-no! Well, the half-inch and three quarters have the same TPI, so if you're short on options... just pretend I didn't say anything.
Some standards now:
DIN - Deutsches Institut für Normung or Deutsche Industrie Normen (German Industrial Standard). We use this one all the time - like, can you order a coil with the DIN connector? DIN includes thousands of standards, so I guess this phrase doesn't make much sense, and in fact, the DIN 43650 connectors that we usually use can come in forms A, B, and C.
SAE - Society of Automotive Engineers which is now SAE International - a huge international US-based organization responsible for thousands of standards.
ISO - International Organization for Standardization (has headquarters in Geneva).
To tell you the truth - it's all mixed up for me at this point. So, in my head - SAE means American and Inches and DIN means European and Meters. For example - an SAE hydraulic motor or pump flange will have its pilot diameter in a meaningful number of inches (e.g. the SAE "C" flange, which has the pilot diameter of exactly 5 inches), while a DIN flange will have its pilot in a meaningful number of millimeters (e.g. 125mm or 160 mm). By the way - all these flanges are described in ISO 3019 slash one and two standards, so I guess ISO is a winner here.
Feeling confused yet? Don't worry if you are - you're not alone.
Other abbreviation you may find (in no particular order):
NFPA - National Fluid Power Association
UNF - Unified National Fine (the thread that you find on JIC and ORFS fittings, its external diameter is its nominal diameter in inches, so no "funny business" here like with the BSP. Which is why I like UNF better.)
BSW - British Standard Whitworth.
EN - European Norm (European Standard)
CETOP - Comité Européen des Transmissions Oléohydrauliques et Pneumatiques, whcih is the European Fluid Power Committee
I will be extending this list as I remember or come across more abbreviations, but if you have suggestions or think that I missed something interesting, please, let me know!