A NOTE ON BLACK OXIDE FITTINGS:
When a liquid inside a fitting is highly pressurized, it exerts a uniform force on the inside surface of the fitting, resulting in a radial stress inside the adapter material. As a direct result of this radial stress, the fitting will slightly increase in diameter, causing it to decrease in length. This decrease in length can have a noticeable effect on the high pressure joint and make it prone to failure.
This effect we call the "Poisson's Ratio", and when we design an adapter we must factor in restraints such as material mass, orifice size for flow, and, of course, application restraints that limit this effect to a ratio of no greater than .5 of mass, in order to maintain the integrity of the joint.
This effect is generally not a problem when dealing with hydraulic systems that are running pump ratings in the area of 1500 to 2250 psi. Although our fittings are, in most cases, capable of holding pressures in excess of this, it cannot be done without coming close to, or exceeding, Poisson's ratio.
In an attempt to limit this natural consequence of physics the industry as a whole has simply reduced orifice size to offset this effect. We ourselves have done this on occasion to accommodate a customer with a special pressure requirement. This in turn creates a flow restriction problem that in some function situations are unacceptable.
To overcome this obstacle, Adaptall has developed what we call a "K" fitting. Through a unique combination of material selection and heat treatments, we can now provide an adapter that limits the Poisson's Ratio to .287 of Mass @ 10,000 psi, virtually eliminating joint fatigue as a result of elongation, with little or no restriction in flow. The "K" fitting also has a black phosphorus and oil finish providing excellent lubrication properties that help prevent thread galling.
In addition to their striking black color, "K" fittings have a grooved notch system that differs from our normal product.
- In the case of a K9235, with tube, one groove limited to 6000 psi.
- In the case of a K9235, without tube, two grooves limited to 10,000 psi.
- In the case of 9035, one groove limited to 10,000 psi.
With the recent development of our burst tester we were able to proudly confirm the predicted results of this new product development.
The introduction of these products is a result of the profound recognition of the tendency for increased pressures.
ALL BLACK OXIDE FITTINGS ARE P.O.R