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Old 12-17-2007, 05:13 PM
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shunut shunut is offline

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Default What you need to know to fill your own tank.

I've noticed a lot of people wanting info about filling their own tank so I thought I'd look around and see what kind of info I could find. I came across 1 thread on PBN so I decided to bring that info over here.

Originally Posted by TargetIndy from PBN

The purpose of this thread is to answer all the commonly asked questions about filling compressed air tanks. This thread is split into several posts, broken down by category. This first post will explain the basics of air fills, and the options available. The posts following this one are FAQ's, specific to each type of system. The FAQ's break down as follows:

Types of Fill Systems (in order of set-up cost, lowest to highest)
Scuba Tank ($200 - $500)
Bulk Tank/Cascade ($500 - $2000)
Booster ($2000 - $4000)
Compressor ($4000+)

Frequently Asked Questions--General

Can I fill my paintball tank with my shop compressor?
No. Most shop compressors run at 125-150 psi.

Can I use a booster with my shop compressor to fill tanks?
No. Boosters require two pressures of air to operate--drive air and supply air. While you can use your shop compressor for the drive air, you still need a higher pressure of supply air. To operate efficiently, you'll need to provide a supply air pressure of 1000 PSI or higher.

How do I determine what type of fill adapter I'll need for my supply tank(s)?
Stamped on the valve of the supply tank is a CGA number. This number is what you'll need to purchase the correct adapter. 2200 PSI bulk tanks commonly use a CGA 580 or CGA 680 adapter.

Frequently Asked Questions--Scuba

Where can I buy a scuba tank?
Your local scuba shop, Ebay, and other online stores are good sources for scuba tanks. When buying used, keep in mind that scuba tanks must be hydro'd and visually inspected on a periodic basis. A used scuba tank may have a limited service life.

How many fills will I get off a scuba tank?
That all depends on the size (in cubic feet) and pressure of the supply tank and the size (in cubic inches) and pressure of the tank being filled. Two excellent resources are this chart and this Java-driven calculator

Where can I get my scuba tank filled?
This will depend on your area. Scuba shops are an excellent choice, though some may require that you be a certified diver before they'll fill your tank. Other places to talk to are your local compressed gas supplier or a welding supply shop. In some cases, I've also heard of fire departments being willing to fill scuba tanks. You may also be able to work out a deal with a field/store owner.

How much should I expect to pay to fill my scuba tank?
That'll depend on where you get it filled. Prices ranging from $5 to $30 are not unusual.

Bare Bones System
A bare bones sytem will consist of a single scuba tank and fill adapter (commonly referred to as a yoke).

Frequently Asked Questions--Bulk Tanks/Cascade Systems

There are two ways to fill from bulk tanks--the single tank method and the cascade method. Common to both systems is the need for a fill station and a regulator. The fill station will provide the connection between the supply tank and the fill tank, while the regulator will control the maximum pressure to the fill tank.

Single Tank Method
The single tank method is exactly that, filling a paintball tank using a single supply tank. Aside from scuba tanks, this is the cheapest system to set up.

Cascade System
The cascade system uses two or more bulk tanks to fill a tank. In a cascade system, each tank is connected to a main line, which supplies the fill tank. The tanks are opened one at a time, starting with the supply tank that contains the lowest pressure. Once the pressure between the supply tank and the fill tank equalizes, the valve is closed and the next tank is opened, stepping up the pressure. The process is repeated until the fill tank is filled.

The cascade system allows you to use more of the air volume supplied in the tank. Once a tank gets to pressures below 500 PSI, it is removed from the cascade system and a new tank is connected (becoming the highest pressure tank).

Where Can I Get Bulk Tanks?
There are two routes you can go. The first, and cheaper, route is to rent tanks from a compressed gas supplier or welding supply company. Typically there is a daily rental charge and fill charge associated with renting tanks. The advantage is that your supplier will typically deliver full tanks to your location.

The other option is to purchase your own tanks and take them to your supplier to have filled. Purchase prices for bulk tanks range from $350-$1000 per tank. This is more expensive to set up, but it will save you the daily rental and delivery charges.

Bare Bones System
A bare bones sytem will consist of a single bulk tank, rented from a gas supplier, and a fill station. When renting a tank, you'll want a 4500 PSI nitrogen tank. You can find these tanks through gas suppliers or welding supply companies.

Frequently Asked Questions--Booster System

A booster system is a machine that uses a larger volume of lower pressure air to compress a smaller volume of high pressure air, thereby increasing the pressure of the high pressure air. This is accomplished through the use of air driven pistons.

Boosters come in two styles--single action and dual action. A single action booster will have one high pressure piston and one low pressure piston. A dual action system will have two high pressure pistons slaved to a single low pressure piston. Dual action systems are more efficient and can support a greater number of fills per hour.

Bare Bones System
A bare bones sytem will consist of a single bulk tank, a shop compressor (100 - 150 PSI), and a single stage booster system. When renting a tank, you'll want at least a 2200 PSI nitrogen tank. You can find these tanks through gas suppliers or welding supply companies.
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Old 12-17-2007, 05:14 PM
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shunut shunut is offline

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Default Re: What you need to know to fill your own tank.

Originally Posted by TargetIndy from PBN

Frequently Asked Questions--Compressor System

When purchasing a compressor, there's a lot more to consider than how much air it can push.

Compressors use a series of pistons, called stages, to increase the pressure of a given volume of air. High pressure compressors typically have 2-5 stages. When you look at a compressor, you'll notice that these pistons are different sizes. The largest piston is the first stage, taking atmospheric air and compressing it to a higher pressure. The higher pressure air is then passed to the next largest piston. The process is repeated until the air reaches the final stage (smallest piston). Most of the pressure increase occurs in the final stage, with some compressors increasing pressure at the final stage by as much as 4500 psi.

Duty Rating
Perhaps one of the most over-looked items when purchasing a compressor is its duty rating. Simply put, a duty rating is the amount of time a machine can be run in a one hour period. A compressor with a 25% duty rating is only meant to be run 15 minutes out of every hour. Exceeding the duty rating of a compressor can greatly reduce its service life, due to overheating and other maintenance issues. Smaller, portable compressors typically have a lower duty rating.

Drive Types
Compressors are typically powered by one of three methods: electricity, diesel engines, or gasoline engines.

Each power system has its own advantages, and your application will help to determine which is best for your situation.

Electric compressors are usually powered by single-phase or three-phase, 220V. While three-phase motors use electricity more efficiently, not all locations have three-phase 220 available (particularly residential and rural areas). Single-phase 220 is typically available wherever there is access to electricity.

Easier to maintain than systems using an engine. System can be easily set up to automatically start/stop when pressure reaches a certain point. Can also be quieter than other options. No issues with exhaust.

Not a good option for mobile operations.

Gasoline Engine
Most mobile units use a gasoline engine to supply power to the compressor. If a two-cycle or four-cycle engine is an option, go for the four-cycle.

Self-contained and very mobile. Cleaner than diesel

Dirtier than electric. Should only be used outdoors. Not as reliable as other options.

Diesel Engine
While similar in advantages as a gasoline engine, diesel is better suited for high-torque applications such as air compressors. The same amount of torque can be had from a smaller diesel engine than a larger gasoline engine. Diesel engines also have the advantage of being simpler to maintain (fewer parts than gasoline engines) and longer service lives.

Best option for larger compressors when electricity isn't available. Simpler design than gasoline engines means fewer items to fail.

Dirtiest system. Can be hard to start in cold weather applications (sub-zero).


Condensate Drain Systems
Most compressor systems come with some form of a condensate drain system (CDS). CDS's remove moisture from compressed air. Failure to remove moisture can damage your compressor and/or fill station components.

CDS's come in two types--manual and automatic. A manual system requires the operator to manually drain collected moisture. An automatic condensate drain system will drain water automatically. Having owned both types, I strongly recommend going with an automatic system. As a field or store operator, there will come a time when you'll forget or be too busy to maintain a manual system. An automatic system is cheap insurance compared to the cost of having a compressor repaired (my local repair place charges $72 per hour for labor).

Aside from regular maintenance, filters are the best protection of your investment that money can buy. Dirty, unfiltered air can damage compressors and air fill components. Air should be filtered at the intake point (prior to the first stage) and after compression. If bulk tanks are used for air storage, a filter should be placed downstream of the tanks to collect rust and other debris that can settle in the tanks. I also use particulate filters on the fill whips to prevent debris from being inadvertently transferred between the user's tank and the fill system.

CFM vs. SCFM (source: Wikipedia)

CFM is an often confusing term because it has no single definition that applies to all instances. In the most basic sense, CFM means cubic feet per minute. Sounds simple enough right? Unfortunately, air is a compressible gas. To further confuse the issue, a centrifugal fan is a constant CFM device or a constant volume device. This means that, provided the fan speed remains constant, a centrifugal fan will pump a constant volume of air. This is not the same as pumping a constant mass of air. Again, the fan will pump the same volume, though not mass, at any other air density. This means that the air velocity in a system is the same even though mass flow rate through the fan is not.

Standard Cubic Feet per Minute (SCFM) is a volumetric flow rate corrected to standard conditions of gas density, thus representing a precise mass flowrate. SCFM is volumetric flowrate at a “standardized” pressure, temperature, and relative humidity. However great care must be taken, as the "standard" conditions vary between definitions, and should therefore always be checked. The “standard” conditions are usually defined as 1 atmosphere (101325 pascals, 1.01325 bar, 14.7 psia) atmospheric pressure, some temperature (e.g., 68°F) depending on the "standard" used, and some relative humidity (e.g., 36%, 0%) depending on the "standard" used.

The temperature variation is the most important. In Europe, SCFM is normally defined as "Standard Temperature and Pressure" (STP), which is 0°C, 32°F. In the USA, however, ambient conditions are used as a basis, and different groups use 60°F, 68°F (20°C), 70°F and 77°F (25°C). SCFM defined in this way can be nearly 10% greater than the European values. For example, a mass flow of 1000 kg/hr is 455 SCFM defined at 0°C, 32°F but 489 SCFM defined at 68°F, 20°C, which is the most common US basis.
Otter also has some info on his site about filling tanks, both co2 and HPA:

Filling you Tanks

Here are a couple websites that I have found that I thought could be helpful if you are trying to put your own filling station together:

Reliable Air

That is all I have for now as I get more info I will add it. If you would like to add to this please do.
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