Direct Comparison of 3 types of Harbor Freight Blast Cabinet Upgrade Metering Valves 

Many thanks. Glad you got a lot out of our video. Happy blasting !!

Your correct its called ventury effect increase velocity

The venturi effect does describe this phenonmenon in general. However, remember that the media flow is essentially a slurry mixture of air and small solid particles (the media) and frictional loss plays a significant role here unlike in a carburetor venturi where the mixture is highly atomized droplets of liquid suspended in air. It is because of the frictional loss in the system that the larger bore of our high flow metering valve plays such an important role in increasing flow and providing better performance Hope this explanation helps

Thank you Mr. Bernoulli.

@@partswasherupgradekit6028 The different media (sand,glass,soda ash,walnut hulls)all have their own set of demands

@@budd1814 That is correct. IN addition, the grit size will also have an influence. Regards

Thx. We try to call 'em as we see 'em. When we have the chance, we plan on doing a flow test to get some solid numbers to put against all three and see how they compare in a heads up comparison. We do put a bit of a cone shape into the threaded end of the brass barb. What we have learned from experience is that if we cut too much out of the inside of the threaded portion of the brass fitting, the threads can buckle as we tighten it to our torque specs. So, like many things, it's a matter of trade offs. Greatly improved yet still strong. Thanks for your comments and stay safe out there.

@@partswasherupgradekit6028 after the step drill cut in the fitting you could use a tapered reamer to take down the steps for smoother flow.

@@mrrberger Actually we do not use a step drill. We use a carbide tapered reamer just as you suggested. So there are no steps. We don't remove the entire flat end of the fitting but do thin it way down. We found through testing that if we take out all of the end wall of the fitting, the threads can collapse as we torque the fitting which then causes the threaded portion to bulge out into the flow stream. Thanks for your comment Regards and happy blasting

@@partswasherupgradekit6028 Thanks for the correction, I was looking at 8:50 and the example has steps in it so I made the wrong assumption.

You are very welcome. We are delighted to hear from our customers and learn of the improvements that our products make. Happy blasting !!

many thanks.

Your purchase is much appreciated. And yes - ordering through our website saves the Ebay fees which have gotten pretty high. Happy blasting !!

Many thanks!

Thanks! 👍

Thanks for your kind comment. We do our very best, as a family owned business trying to survive Covid-19, to offer great kits and components at the very best prices and to provide helpful service to our customers regarding installation and operation. Have a great day and thanks again the Team @ BESTTOOLUPGRADES

Glad it was helpful!

Been a few months now and still works really good just making the one myself out of pipe! Never run out of sand like I was before - just thought you'd like a honest update :)

@@y2kdano Much appreciated. Happy blasting !!

Thank you! You too!

Glad it was helpful!

Thanks for your thoughts on potential improvements.

Good idea.

Glad you liked it!

@ Keith - we hope to do the flow testing in the near future. Please subscribe to our channel if you haven't already so that you will be notified of all of our future videos. Take care and happy blasting !!

Thanks. Hope you will subscribe and follow our channel as we add new videos about our products and how to install and use them Happy blasting

Thanks for watching !!

You're welcome!

Thanks for your comment. In isolation that could be correct. However; this valve is part of a full vacuum system and there are multiple places where the ID narrows down, to include the actual venturi in the body of the blast gun where the vacuum is created. With multiple restrictions (venturis), pulses can be set up which invariable interfere with each other. Boring out the metering valve actually smoothes the flow upstream of the gun body, thereby increasing the overall efficiency of the system. Thousands sold with very happy customers. Best regards

Awesome, thank you! Glad the video was helpful. It is important for us to try to provide an understanding of how these tools work in order that the guys who own and operate them can get the most out of them as well as to understand how our products help make the basic tools much better. Appreciate your order. Please reach out to us with any questions Regards

which one did you order and what are your thoughts on it

@@partswasherupgradekit6028 I have been using your upgrad kit now for sometime and have to say that it makes ALL THE DIFFERENCE IN THE WORLD. Thank You for a great product!!

@@CarlosDelaoGunEngraver I bought the one that the videographer built and it works great...

@@w.w.2restorations.vehicles698 Many thanks for your purchase and comments on the quality of our products. Happy blasting !!

Many thanks. Happy blasting

Thanks for watching.

Thanks for watching and commenting

I see it could work but the valve is rarely adjusted once the cabinet is dialed in. Best regards

I was just thinking the same thing. Great minds!

You're welcome 😊

Thank you for your comments but we feel compelled to provide the following. 1) Yes, this could be seen as a venturi but it is not helpful as such. Why not? Because there are multiple places in the full cabinet system where internal diameters change and each could be considered a venturi for the purpose of speeding up flow. However, when there are multiple constructions along the fluid pathway, induced irregular pulsing can take place causing interruption in flow. Our bored out throat area eliminates one such example and smooths flow overall across the entire system. 2) The media particles are constantly bouncing off each other in the air/media 'slurry' and the flat face of the base of the brass fitting is absolutely being struck by the media particles. This badly interrupts the flow. The proof of this is easy to see by the disassembly of valves that have not had this modification. The face of the base of the fitting shows wear that was caused by this particle impact. We appreciate your efforts to provide additional information and knowledge to potential users. However, when that information is incorrect, it has the opposite affect. Thank you for your last comment wherein you note that our modifications do indeed increase efficiency. Regards.

@@partswasherupgradekit6028 on point 1) : it's bad design if there are irregular diameter changes across the cabinet. The venturi effect will be the most useful where sand is being mixed with air as this introduces also a lower pressure zone. That's why fuel is mixed there in carbs and same principle is being applied in pneumatic conveying, which is my background. See dilute phase conveying (low pressure, high speed gas flow). With downstream bad designs, you're just losing the effect... just like having intake manifold made of porous material susceptible to trap fuel. On point 2): The brass is going to erode starting from the edge, where the stagnation point transitions to flow lines and will do so also on the modified one. The entire face will not erode simultaneously. I do however realize the effect of removing all obstacles, but the initial smaller design did not really mind this unmachined face. It became a problem after the body was enlarged. I appreciate what you're doing and generally the product is improved with these modifications - if what you're measuring is the rate at which e.g. rust is being removed from a surface. I do however want to challenge what's being told here and why exactly something is improving. I might learn something myself.

We are happy to try to assist you if you can provide a few more details on your setup. Thanks for watching

Bingo -

@Darren - thanks for your kind comment. 90 PSI is quite high for pressure at the cabinet. Try dialing it back to 45 - 60 and see if that helps. More pressure is not necessarily a good thing. Have you dialed in the air bleed valve on the metering valve? We will be uploading a new video soon that shows the process of dialing in. One more thing - the guns that come with the HF and many other entry level blast cabinets are, well, ..... crap. It may be a gun issue, not a metering valve issue. Keep us posted and we'll try to help you solve the problem. After ensuring enough air flow (CFM) at the correct pressure (and with dry air) It's always a matter of some component not working properly. Hope this helps. Stay safe out there

Thanks for your order. We supply a hose kit option with the exact spec media hose, grommet and hose clamps. Please see our website under "parts and accessories".

Need to know more about your setup as other components play a big role in the overall performance. Which gun are you using? The stock HF gun is a poor design and is often the cause of the problems you are seeing. We sell a great upgrade to that gun Please contact us at partswasherupgradekit@gmail.com and we will be happy to help you regards

Thx for your comment. Galling could be a problem in some circumstances but the drain plug only needs to be turned in finger tight to keep the media from leaking out. Therefore the liklihood of galling in this situation is extremely low. Would not recommend the use of a thread sealant as this could contaminant the media and cause a clogging of the gun orifice. best regards

Do you by chance have a link to a site that describes this in more detail or perhaps has pictures?

i'm not convinced that it would be better. I think it will suck to much media and clog the pipe or the gun. It may help when people use a weak compressor with not enough flow. Would need to take the air from the pedal control so it would stop sending air as you stop blasting.

We doubt that this would work because the media would probably block the air flow completely rather than the air flow pulling media particles from the leading edge of the pile. Thanks for your thought

yep. Tapping must be precise because the thickness of the wall of the tube only allows for about 2 complete threads.

Nope. With our valves it is just not needed and might actually work against the efficiency of the valve hope this helps thanks for your question

A few thoughts that might help: 1) how much media is in the hopper. Do NOT want more than a couple of cups while dialing in the system - then increase. 2) If you have 110 PSI at the cabinet, it is too much and could be hiding another problem (45-65 PSI is generally good) 3) What gun are you running? Please see our video on the OEM HF gun (it is generally a POS) and another of our videos on cheap Chinese knock off guns also with problems 4) 5/8" hose is pretty big especially if you have a smaller compressor as it creates too much dead space volume and there is not enough vacuum to get steady flow 5) Is the gun orifice size matched to the output specs of your compressor (if not matched it will not work well and could cause the surging that you are seeing. 6) Watch our video on dialing in of your metering valve. Only takes 10 mins and once dialed in you are good to go Overall thought: All the components of the blast cabinet system need to work together to achieve proper performance. Changing out one may not result in desired results because other parts are not playing well together. Changing the metering valve to one with a better design can result in weaknesses elsewhere in the system being exposed. Hope this helps Best regards Ron Best Tool Upgrades

@Todd Sorry to hear you are having a problem. Not too much to go one but look at the gun for a potential issue causing the vacuum to be reduced with potential air backflow down the media tube instead of up. Feel free to contact me at partswasherupgradekit@gmail.com to go into a bit more depth and get you up and blasting again. Also check out my website at partswasherupgradekit.com for all of our great blast cabinet and parts washer upgrade kits and individual components Stay safe out there

@@partswasherupgradekit6028 Yup I pulled the gun apart last night and sure enough the o-ring was torn. But my metering valve keeps clogging as well I'll take a look at yours

Yes. I have had several of my customers install this on the bench top model

Thanks for your kind comments. We are currently having a problem keeping enough of the our high quality guns in stock so we have not listed them separately. That said, please reach out to us at partswasherupgradekit@gmail.com with your request and we'll see if we can help you out.

Hard to diagnose but usually this means that there is not enough suction. What gun are you running? What orifice size? Also what size compressor (in cfm)? Could also be too much media in the hopper. If you send additional details we can try to help you out regards

Working on it thx for asking

Yes - air inlet valve is absolutely essential to proper functioning. Also the HF gun is a terrible design if you are still running it. See our other videos for direct comparison with our high quality gun. Hope this helps

We do not have a quantitative assessment as compared to the old siphon tube. However, the difference is so great and immediately noticeable that our customers report that they can't believe what a huge difference it made

Thanks for your question. I took a look at this model online and yes, this should work just fine on the B40. Getting rid of the siphon tube is a great mod for any blast cabinet. FYI - the gun that comes with the B40 is rather poor. The gun we supply with ALL of our kits that come with a gun is very similar to the gun that Eastwood supplies in its top of the line model B100. That cabinet is much more expensive. With our upgrade kits, you can take a basic blast cabinet and turn it into a MUCH improved one with muchbeyter performance. Please visit our website at www.partswasherupgradekit.com and see all of our products Thanks again

Dan - replied to your email. Hope I understood your question correctly. Ping me back if you need additional info. Thanks for your question and interest

Thanks for your question. The cast aluminum metering valve is a purpose made part for this application. I have never seen it used for another purpose (but someone may have gotten creative with it !!). Happy blasting

@@partswasherupgradekit6028 Interesting thanks!

Jay We have had our customers use our kits and all components on the HF bench top model. Takes just a tad of creativity but they report excellent results. Let us know if you have additional questions. Happy to help.

@@partswasherupgradekit6028 Thanks Ron, I've already sized it up yesterday and it will definitely work! 👍👍thanks for the reply my friend and I'll probably be making more purchases in the near future. 🙂

It would be really helpful if you could make a video showing HF Benchtop valve installation 😉

Sorry - we currently do not offer an upgrade for this application

Thanks for your comment. No real need to clean the threads as the fitting never really needs to be removed. Also, if the threads were external the fitting would require a large reduction in size in a short distance to get the 1/2" barb and this might cause a restriction in flow.

Turbulence is good to mix the particles of media with the flow of air. But the pressure equation doesn't really apply here because you have essentially zero pressure (meaning ambient air pressure) where the media is falling into the valve and then there is the beginning of a zone of negative pressure as air comes in the air inlet valve at the top of the metering valve body being drawn through the media hose (kinda like a venturi but this doesn't really describe it because it is more entrainment into a flow with the complexity of the media particles). What is going on inside the metering valve is more complicated than the simply equations that pertain to simple tubular systems. That all said, all of our 3 different types of valves work great. Thanks for looking.

We sell many of the components separately and can also put together a special kit to meet your specific needs. PLease see the drop down menu on our website under "shop all products" and select the subgroup of products to find our products Please let us know if you have further questions

@@partswasherupgradekit6028 OK, thanks. I will go back and look again.

you are absolutely right that this process is like porting a head. Many thanks for watching.

The metering valve does not work under positive pressure, it works under negative pressure (vacuum). Therefore it is sucking up the media, not pushing it up under pressure. Hope this helps to answeer your question

Our modified Hi-Flo is the best. We do the modifications to the basic valve in our shop. Thanks for asking. Best regards

No - that is largely based on the compressor volume

The extra internal volume in the 1" version allows for better media pickup into the air stream and reduces the chances for media backup

Hard to say because there are multiple factors. What media are you using? Grit size? Is air dry? What gun are you using? Happy to help but with your custom parts its difficult to diagnose.

I have a 10 horse Ingersoll rand compressor ,air dryer , princess auto gun , metering valve is a w inch T , and I made a cone ss 2 inch to 3/8" coupling , crushed 20-30 green glass , what else should I let you know ?

@@charles-hr7ir What are you wanting to know? Sorry - unclear as to what you are asking.

@@charles-hr7ir The blast gun is not a particulaarly efficient design. What is the orifice size? The 20-30 grit crushed glass may be the problem. Also, how much media do you have in the hopper (pounda?). Too much can cause packing and creates a log jam. Hope this helps

Sounds like you build yourself a great metering valve. No problem with the strength of these though. Thanks for your comment

@@partswasherupgradekit6028, there's always going to be the one, who thinks he can do it "larger, cheaper & stronger..." Great job!!

i have a 3/4 one on mine and it work well so i doubt that having bigger than 1" is better. Also it's strong enough, no need to be stronger.

Not quite sure what you mean. Are you wanted to blast your flooring tile to clean them up prior to painting or coating? Look into a pressure pot. Used to blast large surfaces outside of the limits of what can fit into a blast cabinet. BUt they are messy. Media goes everywhere as it is not contained within an enclosed cabinet Hope this helps Regards Best Tool Upgrades

Our intention was not to say that the media particles travel back against the flow of the air/media slurry. Rather, that the particles do indeed hit the flat end of the brass fitting at which time they will bounce off of it and then be entrained into the flow. This is considerably less efficient than a laminar flow configuration without obstacles in the way. Hope this clarifies our point. Best regards

I do not think that the geometry of the Y fitting would work. The Tee works great. Thanks for watching

Yes we do. Please go to our website at partswasherupgradekit.com and place your item in the cart and check out. We have sent many items to Australia. If you experience a problem please contact us thanks for watching our video and for your interest in our products Happy New Years

@@partswasherupgradekit6028 Thanks, will be placing an order shortly, thanks for replying

@@dashaB-sl4pu We appreciate your interest in our products.

This ratio is not actually calculated as it is too highly dependent on media type and size, compressor output in CFM, gun performance, etc. Instead, it is important to dial in the cabinet to achieve max media delivery associated with the various components associated with that set up. Hope this helps

Absolutely, Here is the link: www.partswasherupgradekit.com/store/p6/Best-flowing-metering-valve.html Thanks for your interest in our products

@@partswasherupgradekit6028 OK, thanks. I only saw the 4 different kits on your site yesterday..

Yeah. We hear you. International shipping has gotten pretty high. Best regards

yes we do. our website will process the order. we have sent many orders to the UK thanks for your interest in our products

Thanks for your "shocking" comment LOL. Interesting to know if the abrasive media stream will actually eat out the inside of the wall of the PVC pipe and fittings and cause a failure (aka loss of structural integrity). Best regards

@@partswasherupgradekit6028 I thought of that, but that's a future me problem. Besides it's in my home shop, it'll most likely outlast me.

The metering valves we sell convert a siphon tube cabinet into a gravity fed one. MUCH better efficiency. Best upgrade you can make

It's not a matter of the speed, it's the flow characteristics of the airstream when loaded with particles (the abrasive media). The venturi effect in a traditional carburetor creates negative pressure drawing in the atomized vapor (gas and air), What is going on inside the metering valve is a different matter. Also, once the airstream with the media hits the larger ID of the hose, it will slow down and therefore keeping flow speed up with minimal internal friction becomes a ket issue. Thanks for viewing and providing your comment Regards The Team at Best Tool Upgrades

@@partswasherupgradekit6028 thanks for the info, makes sense now.

I think you mean Bernoulli's Principle. And yes that is correct; however, the area of reduced diameter is followed immediately by a long section with increased diameter, therefore the increased speed is very limited. What is more applicable is the concept of constricted flow and our milled out valve reduces the construction. Also, remember that this is not a simple fluid. It is a fluid with high levels of suspended solid particles (the media) so internal frictional forces are an issue. Bernoulli's is best seen in a carburetor where the faster flow creates an area of lower pressure and that comparative vacuum then pulls (sucks) in atomized fuel. Different from a metering valve that in entraining solid particles within an air stream.

The use of an aftermarket metering valve in this location is quite common. We ourselves have sold thousands of them and never had a single comment regarding the inability of the trap door to support the weight. When you think of the hopper being commonly loaded with 20-30 pounds of media (or more in some cases) being held up by the trap door, the additional couple of pounds from the metering valve is really negligible overall. Appreciate your comment and thanks for watching our video. Best regards

We appreciate your comment. In reality, it's not that easy to purchase all of the parts. The air inlet valve is not typically sourced locally and tapping requires an odd sized tap. Taps are not cheap. Also, tapping the relatively thin wall of the pipe is not that easy for most people as there are only about 2 and 1/2 threads worth of thickness. The box stores don't carry all of the parts and even if they do, rarely have them all in stock at the dame time. We have had several people contact us after building one themselves to tell us that, in hindsight ,they wish they would have just bought one from us. Not much more money after sourcing all the parts and zero in time and aggravation driving around town and ordering online. Not saying that it can't be done by a handy guy for less money, but for many, time and troubleshooting is not worth the savings. Again, we do appreciate your comment. Just want people out there to know it is not just a run to Lowes and 10 minutes back in the garage. Happy blasting!!

Well, today had some extra time and made me one. Works like night and day..

Glad this helped. Please visit our website at www.partswasherupgradekit.com to see all of our products. Happy blasting

Suggest that you whitelist the site with your virus protection platform. Sorry for the inconvenience

Thank you for your comment and the opportunity to explain "our physics" from "your physics". Simply stated - "your physics" is the physics of looking at an isolated component of a system and drawing inference as to how it might impact system functionality. "Our physics" is to look at ALL of the components of a complex, dynamic system. We do not need to debate Bernoulli. But when and where Bernoulli is of value in terms of increased system efficiency needs some discussion. The increased flow speed, which also decreases pressure, can be very helpful in such classic examples as a carburetor where gas molecules are introduced into the stream of air at the venturi. But take a close look at the full cross section of the metering valve. In the unaltered valve, there is a restriction in the throat of the valve followed by an increased cross sectional diameter, followed by another restriction in flow created by the ID of the brass fitting, followed by a long distance of increased diameter that is the media hose. What you can't see is that there is another restriction at the other end of the hose at another brass fitting, and yet another tunable venturi that is designed within the body of the media gun itself. Repeated sequencing of the speeding up of the flow, followed by the slowing down of the flow, can create dynamic pulses which can be helpful in some systems, if designed into the system, but are most often detrimental to smooth flow (which is what is desired in the case of media blasting). Now let's talk about what is actually flowing. The stream is not just a gas (air) or a mixture of two gases (air and petroleum distillate as in the case of a carburetor). It is a highly heterogeneous 'slurry' of gas molecules and very large (in comparison to air molecules) chunks of solid media that can vary greatly in size, surface area to volume ratio, and density, depending on what type of media the user has selected and the grit size of that media. Therefore, the system needs to be capable of good performance across a wide range of particle types potentially found in the slurry suspension. The goal is to keep the media particles suspended in a continuous smooth flow of air and not create pulsing or any other condition which could lead to particle drop out from the air stream, which would create clogging (log jam effect) of the system downstream, which then would further reduce flow as a negative synergism. The reduction (not total elimination) of the first and most significant restriction to flow (the throat area of the metering valve) in a system with multiple sequential flow restrictions (aka reductions in cross sectional area) is improving the OVERALL efficiency of the SYSTEM, when all of these multiple Bernoulli 'points', including those in the media gun, are considered. Perhaps we erred in not going through all of the system physics in our video at this level of detail. We will take that under consideration. However, the vast majority of our 1000s of very satisfied customers just want to have their system work to their level of expectation, and are less interested in all of the details (especially when physics are involved, LOL) Finally, we could have had this conversation as an honest exchange of thoughts and ideas between people, but you chose to take the route of snarkiness, belittlement and derision. To that point, no need to tell Mr. B anything at all. He know's what his Principle states, but further, he appreciates the proper application of his Principle to overall system design, not just a single point along a pipe, viewed in isolation. Here's another Principle that may be applicable to the current situation - "Seek first to understand, then be understood" Best regards.

@@partswasherupgradekit6028 Thank you for explaining what you had in mind. I now understand that you, in simple words, wanted to smooth airflow by avoiding dead spots where sudden increases of diameter can lead to accumulation of media. Whether this will get to a point where everything gets choked up or more hinder the airflow might be an experiment that will tell the situation. Anyway from explaining your improvement of a single component I was referring to that only. You are right that sedimentation can take place if solid matter is transported in a fluid or gas stream. As you have explained I understand that the whole arrangement needs to be taken into account. All the connectors with not really streamlined transitions will affect the system performance. Perhaps from your experience the change of one component makes already a significant difference. I lack that experience. Your video seems to hint in that direction. But then you get out that fabricated (assembled from individual components) regulator and state that it might be as good as your product. That makes me wonder whether simply the increased diameter is what makes the system better. The smallest diameter kind of determining the airflow per Watt. Which results for me in two findings: 1. Dead areas can lead to media accumulation which, due to the nature of solids (internal friction hindering easy pick-up), make them permanent or difficult to "dissolve"; and 2. per given power the lower resistance from a larger minimal diameter results in a better system performance. Thanks you again for taking the time to explain. I am not going to comment on any perceived tone.

Thank you in turn for being receptive to our response that provided a fuller context. We do extensive testing on all of our products, use them ourselves in our own home shops and derive high quality feedback from our customers based on their real world experiences. We have learned a lot over the almost 5 years we have been in business and are always looking to find a way to make improvements. Best regards

that is certainly possible but hinging the door down with the hose attached can be difficult and when you open the door the media goes everywhere. So easy to use the screw in plug especially since the metering valve is built around the "tee" fitting. Media falls straight down into a bucket