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Sherwood Regulators 1st Stage One-way Bleed Valves, Sealed Spring Chamber (Small Bubble Stream)
Greg - 4/15/2012 7:38 AM
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Category: Equipment
Comments: 5
Sherwood Regulators 1st Stage One-way Bleed Valves, Sealed Spring Chamber (Small Bubble Stream)I recently purchased a new Sherwood Maximus regulator. When I tested this reg the first time, I noticed a very small stream of bubbles coming from a port with a rubber cap on the 1st stage. I was initially concerned that my new regs were broken. The rubber cap was easy to remove with my finger nail. There were no threads in the port so it’s not like I was missing an actual metal plug. Inside the port hole I could see innards of the 1st stage. I replaced the rubber plug and decided to dive with it in a pool. It worked great!

Latter on I researched this online and discovered that this is how the Sherwood regs are designed. It has to do with the technology they use to keep a balanced reg using a piston design. Some sites said that if you DON’T see bubbles then the reg isn’t working correctly. I also found the following description:

Sherwood’s first stage dry air bleed system is now even better. A first stage must compensate for the change in ambient pressure as we descend. Most other brands do this by allowing sea water to enter the first stage to sense pressure against a diaphragm or piston. Of course, sea water allowed to dry inside causes damage to the chrome plated parts inside. Sherwood senses the water pressure internally by converting it to air pressure thru the dry air bleed system. A small flow of air (10 cc/minute) is allowed to escape thru a one way valve, effectively transmitting the pressure to the piston. The result is much longer life and a faster acting pressure regulator. Naturally, it is important to have your Sherwood regulator serviced by a qualified service center that knows the intricacies of the 1st stage. Tell your service guy that a small amount of silicone grease under the one-way valve helps keep it clean and working. Do not let water get into the 1st stage by dunking it in a rinse tank. A light rinse under a spigot is enough (with the dust cap in place!).

So don’t freak out if your new 1st stage regulator is bubbling a bit. If it has a one-way bleed valve, with a rubber port cap, chances are its supposed to do that. Consult the manufacture’s manual for more information.


DiveBuddyChgo - 7/30/2013 10:27 AM
Do not add silicon grease to the sealed spring chamber rubber plug. It won’t change the stream of bubbles but the grease will get dirt stuck to it. Anyways if there is no stream of bubbles. It needs service beyond what you can do and parts that you won’t be able to get without an auth. Sherwood dealer.
Nitediver - 4/15/2012 4:09 PM
I dove with this reg for several years. A good reg no doubt but I wonder how under pressure it does not allow some water to seep in. I still own my maximus rig and have it serviced each year. This last year new parts were needed due to a small amount of corrosion inside. (First time in 4 years of ownership) Not sure if this is due to other things or the bleed system. My tech was not sure either but it is fixed and ready. By the way 10cc equals .24CF or about 1/2 to 1 min of air for the average diver.
BCorbin - 4/15/2012 10:25 AM
I’m a trained service tech for Sherwood/Genesis as well as Aqua Lung/APEKS. If your dive buddy isn’t already aware of this design approach, it’s probably a good thing to mention to them before your dive. It’s important that they recognize there is supposed to be a very SMALL stream of bubbles coming from the reg 1st stage as a way of keeping water out, but equally important is to notify you if they do NOT see such a stream as this could indicate water can invade the the regulator which could potentially result in performance or reliability issues.......Simple design regulator that works well!
Greg - 4/16/2012 8:07 AM
Thanks BCorbin! After finding out how this reg worked, I told all my students and another instructor about it. Pretty cool concept. I even took the cap off out of the water and applied a bit of silicone to the tip of the rubber cap, I saw someone else recommended doing that. I figured silicone is great on everything.
BCorbin - 4/16/2012 11:37 AM
@Greg, I’m not sure what cap you’re refering to. If it’s the rubber plug, all that will do is possibly reduce the bubble rate. There is a specification for air flow from the bleed port that is measured when the regulator is taken through an annual service (rebuild or not). I’d be careful making changes to these devices w/o some agreement from the OEM.