Metabo HPT, formerly Hitachi Power Tools and known as HiKoki internationally, has introduced a new corded pancake-style air compressor, which they are calling “The Tank.”
The most important thing to know about the Metabo HPT “Tank,” model EC914S, is that it features a 6 gallon air capacity with 200 PSI max pressure rating.
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Metabo HPT says that “The Tank is the Industry’s First 200 PSI high capacity pancake compressor.”
This higher pressure rating allows The Tank to deliver 4 CFM at 90 PSI.
It has the capacity to run several air nailers at the same time – 2 framing nailers, 2 siding nailers, 2 roofing nailers, 3 finish nailers, or 5 brad nailers.
They say “at 200 PSI and 4 CFM at 90 PSI, you can get more work done with less weight.”
Basically, the higher pressure rating means that you can fit more air inside its 6 gallon air tank. Given the same volume air tank, and the same set outlet pressure, a higher pressure compressor will deliver air for longer. Or, as seen with the CFM rating, it can deliver a greater airflow to power more tools and potentially greater power.
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If it helps clear things up, consider the ideal gas law equation, PV = nRT.
Simplifying things (air is not an ideal gas), the ideal gas law says that the pressure (P) and volume (V) are proportional to the amount of substance (n), and temperature (T). R is a constant.
So if you have two 6-gallon air compressors, and ignoring any temperature differences, the one with the higher pressure rating will hold more gas.
Got it? Among 6 gallon air compressors, a higher tank holding pressure means more air in tank.
Metabo HPT says that The Tank, with its specs, will deliver 30% more airflow than other compressors.
It has 2 quick-connect couplers, a metal handle, low maintenance oil-free design, and it weighs 41 pounds.
The 41 pound weight is said to be 22% lighter than Metabo HPT’s traditional EC99S twin-stack compressor, model, although it is unclear why this comparison is being made.
The Tank offers 25% greater PSI compared to Metabo HPT’s basic pancake air compressor, EC710S.
- 6 gallon capacity
- 200 PSI
- 4 CFM at 90 PSI
- Weighs 41 pounds
- 2 couplers
- 1.3 HP
- 13.5A current draw
Price: $199
Discussion
In this image, Metabo HPT’s “basic” pancake-style air compressor is on the left, and the new The Tank air compressor is on the right.
The new air compressor weighs more, but you get 200 PSI holding pressure vs. 150 PSI, and 4 CFM vs. 2.8 CFM at 90 PSI.
Metabo HPT says that this new air compressor delivers 25% greater PSI than their basic pancake compressor, which is true, but if you look at the new model compared to the basic model and its 150 PSI pressure as the reference, the difference is actually 33%.
To be clear, a 50 PSI difference is 25% with respect to the new model, and 33% with respect to the basic model. What this means is that it seems Metabo HPT is being more modest with their specs and marketing claims than necessary.
What all this comes down to is the new air compressor being designed to handle greater airflow and thus greater simultaneous loads from multiple nailers.
For individual users, the higher pressure rating could potentially allow for longer work between air pump cycling, but it could also mean longer fill-up times, depending on motor speed. Fill-up time, cycling pressure, and duty cycle were not discussed in press materials.
With the added capabilities of this new air compressor comes slightly greater weight, and a higher price tag compared to HPT’s “basic” 6-gallon pancake-style air compressor.
Paul
I head desked when I read the specs as 25% more when it is 33%. Good job for catching that and faith in humanity restored. I doubt their marketing is being modest and just made a math error. I see this exact error all the time and it is one that I use as an example in class. THIS EXACT SAME EXAMPLE and 25% – 33% will still get it wrong on the exam.
Stuart
It’s hard to say.
With large companies, marketing typically gets their selling points from product development (how else would they know what to say?), and then legal has the final say. I’d say there’s a greater chance of modesty vs. math error.
Skye A Cohen
Seems nice.. gotta say hitachi/Metabo just seems like they’re going the way of porter cable.. a few old designs that are popular but that keep getting whittled into trash year by year with value engineering, and then a bunch of newer designs are just not professional tools. I was just chatting with a friend that owned a pretty large tool repair and retail company who was telling me that they’re getting swamped with warranty claims and the parts are just abysmal. He was talking about table saws and miter saws but personally I’ve had quite a bit of similar experiences through the last few years with hitachi/Metabo.
I hope they can pull it together I would hate to see another pillar(okay balluster.. wicket?) of professional tools crumble
Koko The Talking Ape
Hm.
I had two thoughts. First was, those scuba tanks hold 3000 psi or more. What kind of compressor do they use?
Second was, is there a law of diminishing returns where the higher pressure gives you more run time, but also means more energy lost through heat? (The air will be heated as it is compressed, but it will cool down eventually in the tank, and as it cools, it loses pressure, so some of the work that went into compressing it is wasted.) And will these air compressors eventually have insulated tanks to help keep that heat from being lost? My freshman physics didn’t cover much thermodynamics. 🙂
fred
Makita sells a smallish somewhat high-pressure (400PSI) compressor:
https://www.amazon.com/Makita-AC310H-2-5HP-High-Pressure-Compressor/dp/B003QP4AFM/
and a few tools that supposedly take advantage
https://www.amazon.com/Makita-AN635H-Pressure-Siding-Nailer/dp/B01HCHJHIE/
When they introduced the idea – they talked about it as the next generation – but that does not seem like it took hold widely.
Gordon
The high pressure stuff is still a niche market, but it’s expanding. More framers are using LVLs and engineered lumber in more places. The high pressure guns are almost required for that.
Bill
The compressors used to fill dive tanks are just specialized versions of a typical shop, reciprocating type compressor. They are three, four or five stage compressors that can pump up to 10,000 psi.
As for the heat of compression issue, you are right that a tank of hot air, at say 200psi, will lose some pressure as it cools. But that is desirable, as you can then pump in some more air with the end result of a greater mass of air at 200psi which equals a greater potential for work. So the goal is to cool the air and make room for more, not keep it hot just to keep the pressure up. Another reason to try and keep the air cool is to better condense out the water vapor in all that hot air, which is harmful to your storage tank and your tools.
Koko The Talking Ape
Well you can still get more air into the tank of cooled air, but that cooling still represents wasted work. You can tell because when the air comes out of the tank, it much colder than room temperature, maybe dangerously so. So the volume of released air is less than it would’ve been, and cold air doesn’t operate your tools any better than hot air. And the air went in at room temperature, and comes out very cold. What did that work? Your compressor, acting as a very inefficient refrigerator.
But if the aim is the maximum air in the tank rather than the maximum stored energy, then sure, let it cool.
Re water vapor, I don’t see why there would be much condensation in the tank. The heated air will gradually cool to room temperature in the tank, so it will still hold the same water that it did in the room, right? Though the air in the tank will be slightly denser. I’m not sure how that would affect the air’s water holding capacity. But unless the air was saturated going in, I bet the effect isn’t big.
But when the air is RELEASED, that’s when the water should condense out (assuming the air were allowed to cool in the tank.) Again, that represents wasted work. If the tank weren’t allowed to cool at all, air would enter at room temperature and come out at the temperature, with the same moisture content, right?
Koko The Talking Ape
And thanks for the info re scuba tank compressors. Multi-stage! They must need some big motors. Or be really slow. Or both.
Stuart
Refer to my earlier comment (below) for more about cooling after air enters the tank during compression.
But, there are other factors.
Let’s say your tank is perfectly insulated or at thermal equilibrium. You’re still going to have cooling as the compressed air expands to ambient pressure.
Room temperature = T1.
Temperature in air tank after reaching equilibrium = T1.
Temperature of air at outlet = T2.
T2 is going to be lower/colder than T1.
I’m probably going to have to dig up my thermo textbooks.
I’d guess that this is due to Bernoulli’s principle, where there will be a pressure drop associated with an increase in air speed. Air speed leads to pressure drop and lower temperature, compounded by volume expansion and pressure drop at outlet?
Stuart
Looking deeper at compressor designs and engineering, there’s a lot involved.
Regarding efficiencies, air compressors are lousy and waste a ton of energy. With commercial-grade compressors, a certain amount of heat waste can be captured and put to use.
It seems a small percentage of waste heat ends up in the compressed air, but that’s the least concern regarding energy inefficiencies.
After giving way too much thought to air compressor temperatures, I remain convinced that you’ll get more cooling at the tank outlet than within the tank itself resulting from the compression process.
Cool air is not about maximizing how much air can be compressed into a fixed volume tank, but a reflection into what can and cannot be controlled as part of the process as you compress air and then exhaust that compressed air to do work.
Bill
Stuart, I think you need to take another look at your research on compressors and compressed air systems. The vast majority of the heat generated in a compressor is due to heat of compression, and that heat is transmitted throughout the system via the compressed air. From stage one to stage two and then to stage three and so on, as it goes out the final stage and the output. This heat is massive and it causes problems.
A simple way to illustrate this is to run a compressor while venting each stage to atmosphere, as is usually done during the run-in or brake-in stage of a high pressure compressor for several hours. During this run-in, you can put your hands on the heads of each stage and find that they are barely warm to the touch. Now, reconnect the interstage plumbing/cooling as well as the final stage discharge and perform a pressure test. You will see that the heads and discharge of each stage will quickly reach an untouchable temperature. All due to the heat of compression. Discharge air temps can reach several hundred degrees quickly. This heat of compression is of course common to all types of compressor designs, including the high volume/low pressure designs of rotary vane and rotary screw compressors.
The problems associated with heat of compression are both internal and external to the compressor itself. On the internal side, there is increased wear and valve failure due to fatigue, oil breakdown and carbon build-up. On the external side, heat impedes the removal of water and oil from the discharge air, both of which can be a problem for components and equipment down the line if not removed. The heat itself is often a problem for equipment and processes in an air system that are sensitive to temperature as well the people using them.
Reducing the temperature of discharge air is an endeavor unto itself. Most commonly, on small shop systems you may see a short coil of tubing that runs from the output of the compressor to a storage tank and that’s all you get. And it doesn’t do much cooling. But when you move to larger commercial/industrial systems where a continuous flow of air is needed, cooling and cleaning that air is a big deal, and is accomplished in an After-Cooler. Large After-Coolers can be a radiator looking maze of finned tubing with a large fan attached and can grow to a water tower or even a refrigerated system. Down stream of the After-Cooler are the separators, desiccant and particle filters. These systems can get large, complex and expensive quickly. All in the sole pursuit of cool clean air.
I will give you that yes, most after cooling is not done so you can cram more air in a storage vessel, but there are exceptions and perhaps I had this in mind when I said as much. This brings us back to scuba tanks. Most dive shops fill your scuba tank with it sitting in a tub or trough of water. This is done expressly to cool the tank of incoming air in order to maximize how much air the tank will hold. In fact, there are even some dive shops that have a refrigerated trough of water to accomplish the same thing more quickly. To a diver, a few more minutes under water is worth the effort and as a diver myself I agree.
Stuart
I’ve been thinking/overthinking this for a few days.
I appreciate your insights!
I’m not sure what I got wrong, aside from simplifying the compression and any tubing between pump and tank as a single entity. Maybe there’s a disconnect between what I know, understand, and assume, and what I wrote in attempt to articulate it.
During compression, the pressure and temperature both increase.
How much waste heat is absorbed by the cylinder and pump head to be dissipated to the environment, and how much is carried in the compressed air?
I have no idea, only knowing that the air temperature inside the air tank is going to be lower than that of the air inside the compression cylinder at peak pressure.
Then, what I was saying next is that the temperature of the expanding air at the outlet side is going to be cooler than the air temperature within the tank.
If you look at the compressor as a black box with air entering at 1 PSI and expanding back into the atmosphere at the outlet at 1 PSI, the thermal energy at outlet will be lower than thermal energy at input, due to energy transfer during adiabatic compression.
I have zilch practical knowledge about scuba tanks, but all that makes sense, about cooling to drop pressure to allow for greater fill and longer diving times.
I’ve been trying to fill in holes in my knowledge about consumer air compressor designs and inner workings, but a vast majority of the information I could find was all related to industrial-scale systems.
Mallen
The heat generated in a compressor, or at least a lot of that heat, is typically removed through an aftercooler between the compression and the receiver tank. I touched the copper tube going to the cooler on a 5hp gasoline engine powered compressor once and got a 3rd degree burn and left some skin stuck to the tube. (Mmmmm someone’s cooking BBQ pork! Or BBQ ape. Smells like one of those.)
Stuart
There are small tankless high-pressure compressors, but they’re used for refilling very small-sized tanks. Scuba tanks will need to be refilled via specialized industrial compressors meant for the task. There are big differences in requirements. Here, this tool needs to be portable, fast, and affordable.
Your question led me down a long rabbit hole. Let’s simplify things, and then you can ask your question again. =)
Also, following is my understanding of how things work, someone please correct me if it’s wrong or inaccurate.
Consider just the air tank. Everything else is ignored. It’s not a compressor, it’s an accumulator. At the inlet of the air tank, air is simply being added. Ignore any pressure or volume changes for now.
In approximations using the ideal gas law, n, the amount of air, is increasing. With volume held steady, the pressure increases. Air goes in, pressure goes up.
If you are only adding air into the tank, there shouldn’t be a big effect on the air temperature.
Now let’s talk about the pump. This is where you have the bulk of the waste heat.
For a piston-based compressor, air enters the piston chamber, and then the chamber volume decreases. Pressure and temperature both increase as this happens. Active or passive cooling helps to transfer as much of that heat to the external environment as possible. I believe this is also why smaller compressors have duty cycles – there is only so much heat smaller compressors could dissipate.
So, pressure goes up, and that pocket of air is pushed through a valve and into the air accumulator tank. My understanding is that, depending on tank capacity and pressure, the air will either experience minimal temperature changes, or if the tank is nearly empty (near ambient pressure), it will expand into the tank and you’ll have cooling.
You will also have water vapor condensation.
If the pressure inside the tank is greater than the pressure in the compression cylinder, the packet of compressed air isn’t going anywhere, the valve would remain closed. So, in most cases, you’ll have expansion as the air passes from the piston chamber to the air tank. So, the temperature of air molecules inside the tank will always be lower than their temperature inside the compression cylinder.
As the tank fills up, each air packet entering the tank should expand to a diminishing degree, with smaller temperature drops as the tank pressurizes to its capacity.
Now, the temperature of the air, as it passes through the piston valve and into the accumulator tank, depends on the cooling of the pump head. You will absolutely have heat transference via conduction. Let’s say you didn’t, and the cylinder walls were perfectly insulated. Then, the air would be heated as it was compressed, and then some of that heat would be retained as the air expanded into the accumulator tank.
With an insulated compression process, the more air that enters a storage tank, the higher the temperature, or rather the lower the cooling upon expansion. This would mean greater potential for thermal losses as the tank would be subject to environmentally cooling..
So, you are correct, but that’s assuming an insulated compression process. An insulated compression process would require an insulated storage tank, and the outlet air pressure temperature would be much higher than ambient air temperature.
As you compress a pocket of air, yes its temperature will increase, but the piston sidewalls will soak up a lot of that heat like a sponge.
It seems what you’re thinking about is an isentropic process, where it’s adiabatic and reversible. Meaning, as the air is compressed its temperature increases and without any loss of this energy. Insulation of the storage vessel would have to be insulated to avoid thermal losses.
Real compressors are not reversible, because you have all of the waste heat lost to the environment.
I would think that heat dissipation is one of the reasons why higher PSI portable compressors aren’t quite the norm. The higher the compression pressure, the more heat that is removed and all that heat has to go somewhere.
TonyT
High pressure air, such as 3000# or 4500# (like I dealt with in a previous job) is for storage, not a working fluid.
Think of the scuba diver – you want as much air in as small a space as possible to maximize dive time. But any reasonably sized HPAC (high pressure air compressors) can’t create much volume. If there’s a leak, it’s quite impressive (and potentially dangerous), which is enough reason not to use it except when really needed. Just like high voltage electricity: do you use 4160V at home? (Or on the job for most of us – the highest I’ve been around is 480V).
In both cases (compressed air & electricity), there can be benefits to going to a high potential energy for transport or storage, then stepping down to a lower level for use, but the costs (including safety) have to be worth it. (BTW, the electrical industry considers low voltage to be 100KV).
If you need a high pressure working fluid, use hydraulics (which are impressive, but come with their own set of problems).
TonyT
Oops…WordPress mangled my comment.
Low Voltage is less than 1 KV
Medium Voltage is 1KV to 100KV
High Voltage is more than 100KV
fred
Compressed air can indeed pose risks. Even at a few hundred PSI you hope that a storage tank will leak before it breaks such that no pieces of shrapnel get scattered about upon a failure. On larger tanks and higher pressures one looks to see that they are ASME certified pressure vessels.
On low pressure systems some plumbers will pressure test using compressed air – but for high pressure boilers (like up to 2400 PSI) – hydrostatic (pressurized water) testing is the safe way to go.
Bill
In the US, all SCUBA tanks are DOT certified (TC in Canada) and are stamped as such on the crown of the tank along with the date of the original certification. Scuba tank are required by the DOT to undergo and pass a hydrostatic every five years after it’s original certification date and a visual inspection, inside and out every year. Without these certifications a dive shop will not refill your tank.
Koko The Talking Ape
It occurs to me that instead of being made As Strong As Possible ™, a storage tank should be Strong Enough ™ and have a relief valve located away from people’s faces, and easily replaceable when it releases or just gets old.
Stuart
I believe most portable compressors have a pressure sensor that controls high pressure shut-off and low-pressure pump cycling, AND a pressure relief valve. Something like this: https://toolguyd.com/air-safety-valves/
I don’t what applicable safety standards call for, but I’d imagine there’s a healthy safety factor where the burst pressure is much higher than the max operating pressure.
Jeffyi
You want heat to be lost. Hot air holds moisture. Half the problem with compressors is figuring out how to cool the air.
As for why we dont use 2000 PSI compressors. You can. Some people do, like those that use glassworking torches that use lots of oxygen that takes hours to collect from the surrounding air and would otherwise need hundreds of gallons of tanks. Those setups can cost $10k+. Our tools run at <90PSI. Air hoses hold 300PSI max. The regulators are made of plastic. Everything would have to be beefed up. Add another zero or two onto the cost of each component. They would have to be mostly stationary. Kinda overkill for the home garage.
Promit
I had a Ridgid 3.5 gallon vertical pancake compressor that was also specced to 200 psi. Oddball model, only really sold for a hot minute before disappearing off the web entirely. I figured it’d be like having a big tank without the bulk. Trouble is the compressor would cycle at 175 psi, so despite the capacity I was eternally listening to a very loud compressor running all the damn time.
fred
My IR shop compressor sits it its own room outside the shop – but you still can hear it throughout much of the house when it cycles on. I’m not sure if I’m recalling correctly – but I think that the many times larger Sullair compressor that we had in one of our shops was quieter. I think the difference was a result of using a rotary screw for compression – compared to the more typical piston on smaller compressors. The Sullair may have also benefitted from the design of its mounts and sound deadening enclosure.
Jim Felt
Stuart.
Did I miss the dB sound level somewhere? To me that’s important. Especially with a little carry around unit like this.
Thx.
Stuart
It’s not published, but I can ask. *done, will follow-up when I know more*
Unless specifically advertised, dB is normally in “definitely wear hearing protection” terrritory.
Yes I have one
Believe I saw 79 db on a spec sheet. They claim it makes a lot of air, didn’t claim it was quiet.
Jim Felt
Yes. And thanks. That’s not even remotely “quiet” in modern portable terms.
But maybe that’s what it took to make it come in at its price point.
Bruce
I keep a small compressor in the garage for air nailer usage. When I need big air, I use a 20lb CO2 tank. It will run a die grinder or impact driver all day long because CO2 is stored as a liquid. It’s about a 700psi tank. This works great for every once in a while usage. CO2 is cheap, but the run to the gas store for refill is annoying.
fred
For a while (ten or more years ago) Lowes was selling a Kobalt version of the JacPac CO2 system to run air tools:
https://www.lowes.com/pd/Kobalt-Portable-Compressed-CO2-Regulator/1040295
https://www.stapleheadquarters.com/ItemForm.aspx?Item=J-6901-91
They also use to carry Blue Rhyno refillable CO2 cylinders
Corey Moore
I certified with a company back in the day who made the transition from ice machines and refrigeration, to liquid CO2 fire suppression, and process inertion systems which displace oxygen in a deflagration susceptible atmosphere with CO2 gas. It was really cool stuff and the entire inertion system worked fundementally like a giant refrigeration loop: A massive tank of liquid CO2 held close to it’s “triple point” was piped in to a process operation (chutes, silos, hoppers) via a series of heaters to acheivements gas formation. Heating obviously causes pressure, and the system was regulated via pressure switches that would cut off the heaters to maintain a formulated pressure just above the CO2’s point of liquidating. The high stakes of the system though, is that triple point when it can be solid, liquid, and/or gas in a small range. So the concern is that exposure to open atmosphere drops pressure, lowering temp, and often flashing hundreds of gallons of CO2 into ice and wrecking it’s containment. I’m curious if it’s more susceptible in great volumes, or if a compromised seal in a CO2 driven compressor would be catastrophic to the tanks as well?
Kent
Higher pressure does nothing for run time, unless the tank is the size of a school bus.
The *only* thing that matters is the compressor unit keeping up with demand. Period. If it can’t compress air faster than you’re using it, it’ll run down.
The initial higher pressure (or larger tank) might give you an additional few moment/minutes of run time, but if you use more than you make, you’ll run dry. Try running a sandblaster or 8″ sander from this, and it’ll fail because the *pump* can’t keep up with the demand.
Just a Guy
They did at least give it a larger pump (4.0 SCFM at 90 PSI) than other pancakes. 200 PSI tank should help you have enough air without it dipping enough to leave nail heads out between gun uses. Will it be enough? We will find out soon enough.
andy
However, for construction, usage is typically more “peaky.” A larger tank or higher pressure can really help when two framers are firing off a volley of nails.
Kent
I’m having a house framed right now, and at least half is cordless. 😉
There’s some truth to what you are saying. The guys are nailing up the siding this week, and there tends to be a lull while they measure, cut, fit – and then nail it all at once. Same for sheathing, subfloor, etc. But with two guys working, they’ve never had an issue with their air capacity.
I may have fallen into the trap of “I can’t think of why it’s useful, so it must not be”.
Nathan
First thanks for putting down the details there Stuart.
Second – I know everyone sees pancake compressors for nailers. I have one I think it maxes at 125 or 150 I forget never use it must past 90
And yes I run it with nailers namely a 15ga and an 18 ga. BUT there was this one time I ran it up to 125 and tried to run an impact wrench. Why – to see it if would since the math says no on the spec sheets but the physics say maybe.
It did take off a lug nut – it would then take another minute to probably pop off another. SO more pressure more capacity. I bet this would run a modest impact wrench – slowly.
Which might be useful for someone. Also it might briefly run a HVLP sprayer. Like say 10 minutes or so. before reressurizing.
Otherwise golly would it air up some tires. I see limited use for it vs other devices for the cost
Perry
If I understand correctly, the comparison to a twin tank compressor is because that’s typically what we use on jobsites for running framing nailers. It sounds like that is the comparison they’re going for.
My concern is longevity. Higher pressures usually mean a shorter lifespan for the compressor itself
Jimmie
It’s interesting that it’s able to deliver 4scfm at 90psi from such a small compressor. That’s not far off from the output from much larger 25-30gal portable belt-driven compressors.
Oflannabhra
What’s the duty cycle on the compressor? At that high of a PSI, it seems like they’d have to have a better duty cycle than typical pancakes.
Bob
Lets hope the tank is thicker too. All the pancakes now seem to have such thin walled tanks. I get a little uneasy with these “certified” tanks being built who knows where with who knows what kind of QC. I have seen what happens when an air tank lets go. Scary stuff.
Does any brand make a high quality pancake style compressor or are they all just considered disposable now? I have heard the “oil less” compressors just don’t hold up long term? I am still rocking a couple 30 year old roll-air and emglo pancake styles that have very thick air tanks, oil lubricated compressors and strong motors. They are heavy and loud tho. Trade offs for everything I guess.