Bad threads on Maid O Mist vents

BobC

I'm reviving this thread to warn people that the current Maid O Mist radiator vents have the wrong size tap on the stem that is supposed to thread into the radiator.



A Hoffman 1A measures 0.372 at the end of the tapping and 0.387 diameter near the vent body. Three Maid O MistsI measured all measure 0.395 at the end of the tapping and  0.402 near the vent body.



I contacted Maid O Mist and was told I'm mistaken, all their vents are properly threaded. I'm waiting for a 1/8-27 NPT die to come in so I can dress the Maid O Mist threads.



Bob

Gordo

And I bet You Were Told

that you are the only person who has ever complained about it.

BobC

Not at all

If they are all made perfectly how can there be anything wrong?



Those vents can come in handy because you can remove the threaded orifice and drill it out for whatever you think you might need. The ones that come with all 5 orifices are perfect for balancing because you can select whatever you want and you can go back to a size without having to go out to the store again.



I've attached a NPT spec below.



Bob

pcloadletter

I thought I was crazy

I picked up a batch of them at HD a few weeks back and had trouble threading each of them into my radiators. I wasn't impressed with them and replaced them with a batch of Hoffman 1A's from the plumbing supply store, which threaded very easily into the radiators. I still have yet to return the MoM's to HD.

ttekushan_3

You are absolutely correct about M-O-M threads

They do not have the proper taper. So they don't fit in the radiator. I have a die on hand just for those vents.



Otherwise, they work pretty well for the money and I like the fact that I can proportionally vent a steam system by changing the orifice only.



The depressing aspect to it (and leave it to me to find the depressing aspect to anything), is that there are plumbers out there (ask me how I know) who instead tap out the radiator threads until the M-O-M fits, thus ruining a lifetime device (the radiator) for an el-cheapo vent.

BobC

I got a reply

from someone at maid o Mist and they said they were going to check the threads to see what's going on. I wonder if they are outsourcing the stems and just getting whatever the supplier ships. I can't detect the difference without a set of calipers.



It is a shame because they are very handy because of the interchangeable orifices, I wish Gorton offered the same thing.



Bob

Paul48

What

does that say about their QC? Even if you out-sourced it, and randomly checked one in 10000, you catch it with the first shipment, and it never gets to the shelves. I discovered something troubling about the company I work for, and it may apply to this as well. We are an ISO certified company, and if a vendor we purchase from is also certified, we do no QC on their materials.

Talk about gambling with your companies reputation, and ability to continue to do business.

BobC

ISO is a schill game

We looked at ISO certification back in the 90's and after reading reams of material it boils down to saying exactly what you are going to do and then do exactly what you said you were. That company shut it's doors when the business went to China but I occasionally get calls about how to fix or use one of their products and it was almost 20 years back that it went under.



It has nothing to do with delivering a quality product, it's just a way to get dollars out of the companies pocket. I used to spend a couple of hours a day out on the production line looking at how things were being done and i used to always find something being done wrong. It's better to catch some thing early because if it gets to the next stage it costs 10X more to fix it.



Rework will put a company out of business really fast, products have to be built right the first time, shipped out and stay out.



Bob

Paul48

ISO

You're right, but you can't do  business in Europe without the certification. It means absolutely nothing, and that is proven, over and over. Without go off on a rant, it is a way to de-value your workers. Anyone can do it....just do A-B-C. After all, it's not about the workers. It's about keeping the shareholders happy.

ChrisJ

threads

Is this true for all MOM vents?



I'm tempted to buy 3 MOM, or "Durst" C vents from lowes to swap out 3 Hoffman 1As on my 2nd floor rads.  I want more venting up there was well as am tired of the vents getting clogged with water.  The Gorton's are a bit out of my reach right now but the MOMs arn't.



Problem is, if I need to buy a die and handle, then obviously its cheaper to just wait and buy Gorton's.



Also, are MOM really good enough?  I don't want to replace my 1A's worth something that will fail in a few short years and wrong pipe threads isn't a good sign.

BobC

Don't know long term

I bough a total of 5 MOM vents from 3 sources and all of the threads are too large, almost like they are straight 1/8-27 and not NPT. I got the 1/8-27 die from amazon as well as the Die handle, the two of them cost about the same as a 12 pack of craft beer so that bumps the cost of my vents up about $3 each in my case.



I've only had them on for a few weeks now so i can't say what the longevity might be but i wanted them because I now have the option to remove the orifice and drill it out to whatever size is need.



I'm not sure why Gorton doesn't do the same thing, it makes stocking a lot easier.



Bob

icesailor

1/8

I'm in Florida right now so I can't get to my tap and die set at home.

But my set has two 1/8" NPT taps. They are as different as night and day. I think that one has 27 TPI and the other 28. Whenever (seldom) I have a problem, out comes the screw pitch gauge. That's where I found the difference. Perhaps it a close difference in inch/metric measurements. But I did find a difference.

I just looked in McMaster-Carr. US 1/8" NPT taps have 27 threads per inch. British Standard pipe taps have 28 Threads Per Inch.

I found some things that were tapped that would not accept standard US NPT threads.

That's probably what you are dealing with. Metric is listed as how many threads per millimeter.

As it slowly comes to me, I have an inch/metric tap and die set. It has both 1/8" taps in it. 1/8" 27 TPI and 1/8" 28 TPI BSPT.

I tried to find a metric equivalent but I haven't been able to.

A inch/metric screw pitch gauge is a wonderful thing to possess.

Hap_Hazzard

QC

No doubt they've outsourced their quality control as well.

Hap_Hazzard

Are you referring to ISO 9001?

ISO is just a standards organization. They don't certify anybody; they only maintain the standards.

Hap_Hazzard

I think you're right about the taper--or the lack thereof.

I installed a couple of new vents this season and was puzzled that they didn't seem to screw in very far. My first impression on unscrewing one was that it looked like MIP but I thought, nahhhh. (My near vision ain't so hot these days.) I thought it must just be some kind of buildup in the tapping, but I couldn't get a tap in to clean out the threads, so I just stuck the vent back in.



I wish I'd had the presence of mind to measure it as you did. I'm away from home for a few days, but I'm definitely going to take another look when I get home.



Let me know how you make out with that 1/8x27 die. I'm not sure if the stem is long enough to run the die all the way down.

BobC

Plenty long enough

I've partially reworked one vent but I'll have to build a jig to hold the vent while I use the die wrench to drive it down. It takes a bit of muscle to cut a thread this size when trying to hand hold both sides. I have got the die down to within 3 threads of the die base using an adjustable wrench on the hex shaped die and there is plenty of stem left below the die.



I'll have the die wrench right after Christmas so I'll post the results and a picture of the jig I'm building. I tried the modified vent in a radiator and it threads in better than an unmodified vent does so when i get all the way down I think I'll be all set.



Bob

Hap_Hazzard

I don't know of any metric pipe thread standards.

The most widely used standard is BSP, which is based on imperial units, like NPT. Pipe sizes are fractional inch, like NPS, but the thread pitch and thread form differ. Actually, 3/4" and 1/2" NPT and BPT are the same pitch (14 tpi) but they still aren't compatible because of their threadforms. What used to drive me nuts is that they're close enough to be mistaken for each other, but if you screw them together, the last thing you get is a tight seal.

icesailor

NPT/ BSPT

Hap,

I ran into it on something. When I went to clean out the threads, I grabbed the wrong tap out of the set. It wouldn't fit. That's when I got out the screw pitch gauge from the set and measured the pitch. It didn't match up. That's when I noticed the other tap in the set. When I compared pitches, I saw the difference. I don't remember if the 28 pitch was marked BSPT but it wasn't the same as the fitting I was dealing with. The tap and die set is from Sears and has both NC, NF and SAE taps and dies. It also has metric taps and dies in it. I find the two pitch gauges to be quite handy when I need them. I have a 50 HP John Deere tractor from Europe that is all metric. By knowing the screw pitch on metric, it is easier to find the correct nut or bolt.

Hap_Hazzard

BSP

28 tpi is the thread pitch for 1/8" BSP, so that's probably what that tap is for. You can't be sure unless you can see the difference between Whitworth and Sellers threadforms. At that size it probably doesn't make that much difference if the threads are taped, but it would be a way to tell what it is. Not that there's much room for doubt. I'm not aware of any ANSI/ASME standard for 28 tpi at 1/8", are you?

BobC

Need a socket wrench

I built a simple jig to hold the MOM vent as I rethreaded it because it takes a bit if torque to thread a 1/8-27 stem; you need either a 1" socket or a 1" wrench because a die wrench will not give you the torque you need.  The vent is 1.9" in diameter and i used a 2-1/8" lockset hole saw because that is what I had on hand.



I used a scrap of 3/4" plywood (5X24)and drilled one pilot hole in the center of the 5" wide scrap towards one end and another about 1-1/8 from that. I then drilled the off center hole with a 1/2" forstner bit to a 1/2" depth. I used a 2-1/8" hole saw to drill completely through the center pilot hole. i added a 1" screw through a 1/4-20 nut to buttress the vent outlet after finding it slipping out of the cavity because of the torque i was using on the socket wrench I was using on the 1/8-27 die.



It looks like two of the MOM vents were oversized and i was glad the plywood was long enough to bear against my leg as I used the 1" socket to drive the die (using oil on the die) onto the valve stem; I would not have been able to hold it my hand. The third just seemed to have excess plating which was pretty easy to rethread.



As you can see there is enough length on the stem to drive the die onto it fully. the rethreaded vents are a bit snug but the thread onto the radiators a lot better now.



Bob

Charlie from wmass

Why would you waste your time?

the time wasted for a short lived vents is silly to me. I buy Vent rites, Gortons, or hoffmans. I install them and move on. I strongly feel if I have to field dress a part I am wasting my time and my customers funds. I am also making a ceo rich and not employing an American worker. If the threads are garbage do not buy them. When they are neck deep in vents they can fix their threading equipment or eat their own vents.

BobC

I agree

It would not make sense for an installer to do this on an ongoing basis, but could be useful for someone who wanted to take advantage of the interchangeable orifices.



They are made in Chicago,I've talked to someone there in the last week.





I hope everyone has a Merry Christmas and a happy and healthy New Year.



Bob

Hap_Hazzard

Guess what.

I got home last night and checked a bunch of my M-o-M vents and they're all standard 1/8" NPT. 27 threads per inch. I can run a die all the way without any special effort. I haven't checked every one yet, but so far they all look perfectly normal.



On the other hand, I found some corrosion inside some of my new, unused vents when I took the orifice out. The valves all work, but still... Not too cool.

ChrisJ

Gorton

And these are the reasons I decided to just order Gorton's.



Its really not worth the extra problems when dealing with the system that keeps my family warm.

BobC

3 out of 5 bad threads

I checked the other two new MOM's and found they both needed some heavy redressing with the die. So that means 3 of the 5 vents i have did not have the right taper, the other two looked like the plating was a bit heavy but easily fixed.



It looks like they had a bad batch recently and i was lucky enough to buy at just the right time. They all are installed and doing the job now.



Bob

Hap_Hazzard

Wait until you get a bad one.

It can happen to anybody. The first Gorton #1 I ordered arrived with a big ol' dent in the body. It might have still worked okay, but they wouldn't accept a return if I installed it, and I wasn't going to take a chance on a $20 vent, so I had to send it back. I don't think this was Gorton's fault, but since no one sells them locally, I have to deal with shipping damage. If I buy a vent locally I can either inspect it in the store (if the seal has been broken) or jump in my car and return it, but I have to settle for the products they carry.

ryoung88

Ah ah

I just picked up a number 5 and the special tool for removal extraction and retreading. New valve doesn't go in right the tool has a female rethreader which didn't work either. Thought I was crazy ... Glad it's not just me

Boiler Talk

Messed up radiator threads

I have one American Radiator that doesn't easily accept the Maid-o Mist or the Gorton.  So I guess that means I could try tapping the hole.  Explain to me if you can buy the 1/8" 27 NPT tool to use on the radiator.  Would the hole be tapered as well? 



I contacted Maid-O Mist and was advised I could bring the vents back for credit.  I purchased them last season.  I could only thread them on about 1.5 turns. 

ChrisJ

tapping

I have a 1/8" NPT tap which i think some refer to as a "pipe tap" or "pipe thread" The tap is tapered which tapers the hole on its own.



I also have a 1/4" NPT tap as well as the required drill bit for it. With that I have 1/4" to 1/8" nickel plated brass bushings. I bought this assuming one of my radiators was stripped as a plumber had told me. Turned out all I had to do was run the 1/8" NPT tap into it a bit and the vent screwed on tight and like brand new.



Either way, I have a backup for if any of mine ever strip and cannot just be cleaned up with a tap.



The 1/4" to 1/8" nickel plated brass bushings came from Mcmaster Carr.



If you look it up you can find the required drill bit for any size pipe tap, in fact I'm positive Mcmaster Carr shows it on their site in the tap sections.

Boiler Talk

Tap, Taper Pipe?

I see tap bits that fit the 1/8" 27 NPT requirement, but I don't know which one I should consider.  Should the tap be tapered like the vent?  Here are two: One looks like it is for hand tapping and the other using a machine, but then I never did this before. 



http://www.grainger.com/Grainger/WIDIA-GTD-Taper-Pipe-Tap-4GT61?cm_sp=IO-_-IDP-_-RR_VTV70300505&cm_vc=IDPRRZ1



http://www.grainger.com/Grainger/VERMONT-AMERICAN-Hand-Tap-2NWN8?gclid=CIPE2aLA2bQCFUOK4AodJlUAIw&cm_mmc=PPC:GooglePLA-_-Machining-_-Machine%20Cutting%20Tools-_-2NWN8&ci_src=17588969&ci_sku=2NWN8&ef_id=UOx0ewAAXX0hVGqS:20130108193315:s

ChrisJ

Taper

Yes it should be tapered, any NPT tap will be.

I would go with the highspeed steel one just because its going to be a better tap and going into cast iron you're going to need a good tap.



The most important things when using a tap are 1: oil and 2: take your time and go back and forth.  Turn it in a little then back it out, then back in more, and back out.

The oil part sucks with a radiator because its going to end up in the boiler which means skimming will be required.





Perhaps others who have used taps more can comment with other tips.