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Introduction

For something that have been around for what seems like ages now, quick disconnect (QDC) fittings remain a mystery to many and find themselves being applied in very few builds. The earlier quick (dis)connect fittings for PC watercooling were based off push-connect air quick release fittings which were intended for higher flow/pressure operations, and that did not translate well here. Since then, however, a lot of manufacturers have gotten aboard the fittings train and today we get to take a look at arguably the most popular ones in the market- the Koolance QD3. Koolance has been around for what seems like ages now, with incorporation in the year 2000, and have a good presence in both retail and industrial OEM markets. My very first fittings included a set of their older twist to lock style QDCs which I have never really been a fan of as for user experience was not as good as they could be, and I am glad to have seen the newer versions adopt something different. Thanks to Koolance for arranging some samples for testing.

Koolance sent some of their QD3 and QD4 quick disconnect fittings, among other things. These are part of their quick disconnect coupling series comprising the QDH1 for smaller tubing/bore size, the QD2 for slightly larger and yet not amicable for PC watercooling, the QD3 which is where most of the attention here goes to, and the QD4 for larger diameter tubing and generally more for higher flowrate industries. All quick disconnect series come as separate male inserts and female bodies with a variety of options including threaded ports, barbs, compression fittings and so on. As such, it is near impossible to have specs for the series as a whole. I requested the QD3 male with 1/2″ x 3/4″ compression fittings and female halves with a G1/4″ male thread in nickel finish, so let’s get more specific.

First up, the QD3 male insert with 1/2″ x 3/4″ compression fitting:

Weight 0.16 lb (0.07 kg)
Materials Brass, Nickel Plating, Stainless Steel, EPDM
Max Pressure @ 25°C 8kgf/cm2 (113.8psi)
Max Temperature 100°C (212°F)

qd3_g1.gif

There’s also a useful technical drawing here and a archived 3D drawing in a .step format here.

Here’s the QD3 female body with the G/14″ with a male thread:

Weight 0.17 lb (0.08 kg)
Materials Brass, Nickel Plating, Stainless Steel, EPDM
Max Pressure @ 25°C 8kgf/cm2 (113.8psi)
Max Temperature 100°C (212°F)

Again, Koolance provides a technical drawing and 3D model. Generally here is where I would start talking about the specs and a bit more but wait, there’s more! You see, there was this issue with the (older) Koolance QD3 (and arguably other series also) fittings in black wherein the internal valve and plunger would be prone to plugging as a result of the black chrome plating flaking off (no personal experience with the older black QD3 fittings, this is based on community feedback from other customers) and also galvanic corrosion in loops with silver and, well, plugging the internals. While it did not affect everyone, a very vocal group of customers rightly complained about this. On top of it, Koolance’s rather stringent warranty policy denying any claims where 3rd party coolants were used resulted in some very upset people. When I first spoke to the Koolance representative about this, I was rather pleasantly surprised in finding out that they made a silent change to the black colored QDCs in order to prevent these issues from happening. I jumped at the opportunity to take a look at the new black QDCs so they also sent what was available at that time- a male insert with 3/8″ x 1/2″ compression fitting:

Weight 0.13 lb (0.06 kg)
Materials Brass, Chrome Plating, Stainless Steel, EPDM
Max Pressure @ 25°C 8kgf/cm2 (113.8psi)
Max Temperature 100°C (212°F)

and a female body with the same 3/8″ x 1/2″ compression fitting:

Weight 0.21 lb (0.10 kg)
Materials Brass, Chrome Plating, Stainless Steel, EPDM
Max Pressure @ 25°C 8kgf/cm2 (113.8psi)
Max Temperature 100°C (212°F)

Ignore the bit about the chrome plating, these are so new they haven’t even had the chance to change the product pages yet. The black is now from paint and not plating, which Koolance believes will hold up longer. But the biggest change is.. nah, you know what they say about a picture and a 1000 words. Next page for that. As before, there are technical drawings and 3D models on the respective product pages.

But wait, there’s still more! I was interested also to take a look at their QD4 series and to see how practical it is in PC watercooling. As such, Koolance also sent samples of the QD4 fittings which only come in 3/8″ (BSP or NPT) threaded or 1/2″ x 3/4″ compression fitting options in nickel or black finish. Since the new black fittings were already covered in the QD3 series above, I went with the nickel finish.

First up (for the 3rd time), a male insert with 1/2″ x 3/4″ compression fitting:

Weight 0.28 lb (0.13 kg)
Materials Brass, Nickel Plating, Stainless Steel, EPDM
Max Pressure @ 25°C 8kgf/cm2 (113.8psi)
Max Temperature 100°C (212°F)

qd4_g1.gif

and a female body with a G3/8″ male thread:

Weight 0.33 lb (0.15 kg)
Materials Brass, Nickel Plating, Stainless Steel, EPDM
Max Pressure @ 25°C 8kgf/cm2 (113.8psi)
Max Temperature 100°C (212°F)

As before, there are technical drawings and 3D models on the respective product pages.

Phew, that was a lot. My plan initially was to have a QDC roundup with 3-4 QDCs in the same article. I very quickly realized the issues with this, and decided to devote an article per fitting type. The QD4 gets bundled in here along with the nickel vs black QD3s though, they share similar internal designs and Koolance is nice about providing a lot of details in the same format. I appreciate knowing the material composition (although slightly outdated in the case of the black fititngs) and the technical drawings. But most importantly, I liked the P-Q charts provided that would give a quick estimate of how many such pairs a pump would handle by themselves and as part of a loop. The various port options are also very appreciated, and Koolance also provides a note mentioning that a minimal fluid spill of 0.2 mL should be accounted for when disconnecting a pair of these fittings. As a rule of thumb, 1 mL has ~25 drops so 4-5 small drops of coolant would really not fall out of the disconnected parts as much as just stick on the mating surfaces. For all intents and purposes, these are no-spill type QDCs. Warranty on these fittings is 1 year from the date of purchase as listed in their warranty policy, which still maintains that their own coolants need to be used in order to preserve warranty. Let’s get straight to this- most customers don’t like this. I had a good, long discussion about this and Koolance made some very good points. I understood how rigorous their testing procedures are for every single fitting, and also how they are really designed for long term reliability. I also understand that expecting Koolance to test compatibility with every single coolant in the market is a bit much. I still don’t like it though. Mayhems, as an example, now sells more coolants for this particular hobby of PC watercooling than most others worldwide. They also provide coolants for other brands including EKWB, Bitspower and Swiftech. Koolance is willing to provide fittings to manufacturers like Mayhems to test compatibility with their coolants which I acknowledge is a good first step. If they have indeed minimized the issues with their black QDCs, that is going to be another, more significant step forward. So without more delay, let’s get right to it with a detail look at these various fittings on the next page.


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