Tweegs
03-25-2016, 10:46 AM
I posted recently about leaking end cap fittings and through the course of discussion, I purchased two replacement caps; a beige colored cap from overseas, and one from Freshwater systems (black).
I have both sitting in front of me now and would like to share a few observations.
In that earlier thread, BreezyHill raised a few concerns over the beige cap. Looking at it now, I can see why.
1.) Outside diameter-The beige cap measures 4.58” in diameter while the black cap is 4.73”. The retaining clamp will have less of a purchase on the beige cap.
2.) Large O-Rings-The beige cap has two large O-rings. The inner O-ring is smaller in diameter than the outer O-ring and the cap itself is tapered between the two O-rings. There is no retaining groove for the inner O-ring. Under pressure, this inner ring will likely roll up the taper, stretching it slightly and therefore present a smaller profile than the outer ring. As such, there is no way this inner ring will effectively seal, rendering it useless. The black cap uses two O-Rings of the same diameter and are mounted in retaining grooves.
3.) Permeate port O-Rings-The beige cap offers a single O-ring in the permeate port, the black cap has two.
4.) Threads-Permeate and concentrate port threads on the beige cap are cut shallow and rounded over, the black cap threads are cut deep and crisp. As a bonus, the permeate port on the beige cap is drilled slightly off center.
5.) Seats-The concentrate and permeate port threads on the beige cap were cut with a plug tap. Threads on the black cap were cut with a bottoming tap, providing a clean and square seat for the fitting with ample material to support.
6.) Concentrate port-The inner portion of the cap which handles concentrate flow on the beige cap is divided into 4 sections. If the cap makes contact with the membrane, there is only 0.06” of clearance between the dividers and the membrane for the concentrate to squeeze through to the other 3 sections. I think this would increase the pressure exerted on the cap whether it was mounted on the inflow or outflow end of the membrane housing, and if mounted on the inflow, would restrict the amount of sap delivered to the membrane in 3 of the 4 quadrants, at least for the first few inches of the membrane. The black cap is void of any dividers.
Obviously, the better purchase was the black cap. The beige cap is going back, I don’t even want it on the shelf as a spare. I’ll use the leaky old cap for that.
1398213983
I have both sitting in front of me now and would like to share a few observations.
In that earlier thread, BreezyHill raised a few concerns over the beige cap. Looking at it now, I can see why.
1.) Outside diameter-The beige cap measures 4.58” in diameter while the black cap is 4.73”. The retaining clamp will have less of a purchase on the beige cap.
2.) Large O-Rings-The beige cap has two large O-rings. The inner O-ring is smaller in diameter than the outer O-ring and the cap itself is tapered between the two O-rings. There is no retaining groove for the inner O-ring. Under pressure, this inner ring will likely roll up the taper, stretching it slightly and therefore present a smaller profile than the outer ring. As such, there is no way this inner ring will effectively seal, rendering it useless. The black cap uses two O-Rings of the same diameter and are mounted in retaining grooves.
3.) Permeate port O-Rings-The beige cap offers a single O-ring in the permeate port, the black cap has two.
4.) Threads-Permeate and concentrate port threads on the beige cap are cut shallow and rounded over, the black cap threads are cut deep and crisp. As a bonus, the permeate port on the beige cap is drilled slightly off center.
5.) Seats-The concentrate and permeate port threads on the beige cap were cut with a plug tap. Threads on the black cap were cut with a bottoming tap, providing a clean and square seat for the fitting with ample material to support.
6.) Concentrate port-The inner portion of the cap which handles concentrate flow on the beige cap is divided into 4 sections. If the cap makes contact with the membrane, there is only 0.06” of clearance between the dividers and the membrane for the concentrate to squeeze through to the other 3 sections. I think this would increase the pressure exerted on the cap whether it was mounted on the inflow or outflow end of the membrane housing, and if mounted on the inflow, would restrict the amount of sap delivered to the membrane in 3 of the 4 quadrants, at least for the first few inches of the membrane. The black cap is void of any dividers.
Obviously, the better purchase was the black cap. The beige cap is going back, I don’t even want it on the shelf as a spare. I’ll use the leaky old cap for that.
1398213983