General Questions

Q -- Is financing available?

A -- Yes, and we recommend the following lending companies:

Q – Are the parts in the HVO System oxygen-rated?

A – Yes. For safety and longevity, we use only oxygen-rated, oil-free parts.

Q How much oxygen fits in a tank?

A It depends on the size of the tank and the pressure. Our "Standard" compressor fills to 100 psi (6.9 bar), whereas the "Mighty Mite" and "MAX" compressors fill to 150 psi (10.34 bar). See the chart below:

Tank Size in Gallons Product Maximum PSI Stored Oxygen
Liters Cubic Meters Cubic Feet
20 Standard 100 594.7 0.59 21
Mighty Mite & MAX 150 849.5 0.85 30
30 Standard 100 877.8 0.88 31
Mighty Mite & MAX 150 1274.3 1.27 45
60 Standard 100 1784.0 1.78 63
Mighty Mite & MAX 150 2548.5 2.55 90
80 Standard 100 2378.6 2.38 84
Mighty Mite & MAX 150 3398.0 3.40 120

Keep in mind that the HVO System replenishes the tank when the pressure goes below 30 psi for the Standard / 100 psi for the Mighty Mite and MAX. The chart above shows how much oxygen is available when the tank is at full pressure.

Q – Is there a warranty?

A – All HVO products come with a 3-year warranty. New Respironics oxycons purchased through HVO are also covered by a 3-year warranty.

Q – What sort of electrical power do I need?

A – The HVO Systems run on standard household power. A dedicated circuit is required for the Master and a separate dedicated circuit for the Relay Box. We sell 3-outlet (requires 20 amps) and 5-outlet (requires 30 amps) Relay Boxes.

Q – How much does it cost in electricity to run the HVO System?

A – It costs about $0.70 USD in electricity to generate the equivalent of a K-tank (based on Portland, Oregon kw rates). Use our calculator to get an estimate based on your specific requirements.

Q -- How do I calculate the electrical usage of my HVO System in wattage?

A -- Add the number of components in your system (ie, oxygen concentrators, HVO Master and Drones). Multiply that number by 550 for approximate wattage. For example, a 20 Mighty Mite and 3 M10s equals 4 components. 4 x 550 = 2,200 watts. For amperage, multiply each component by 5. In this example, 4 components x 5 amps = 20 amps. When calculating usage, keep in mind that the system runs about 50-60% of the time during the course of a work day. Use our calculator to get an estimate based on your specific requirements.

Q -- What is the payback period on the HVO System?

A -- The precise payback period depends on the cost of oxygen in your region, your usage and the HVO configuration. Use our calculator to get an estimated payback period.

Q -- Over a 3 year period, how much will I save using the HVO System instead of compressed or liquid oxygen?

A -- Depending on your local oxygen costs, small shops can save around $7,000, large shops can save around $70,000. Use our calculator to get a three year Return-On-Investment estimate.

Q -- How long can I run my compressor before it needs maintenance?

A -- All compressors need to have their piston cups replaced from time to time. Wear on a piston cup is inevitable due to compression, which causes friction and heat. There is no magic that can change this fact -- it’s just physics.

High-powered, two-stage compressors need piston cup replacements every two to three years, depending on usage. Small low-flow, low-pressure compressors need less frequent piston cup replacement. 

The HVO Standard compressor, for example, runs for a long time without the need for maintenance. In the history of HVO, we have replaced very few piston cups for this compressor.  When service is needed, customers will need to spend 20 minutes and roughly $9 to replace a piston cup*. One customer that needed piston cups for an HVO Standard compressor was running 12-hour shifts, 6 days a week for 4 years. They saved more than $100,000 on oxygen since buying the HVO system, so it’s fair to say they were happy to pay a few dollars to fix their compressor.

The Mighty Mite and the MAX have powerful, 2-stage compressors. Not only do they compress to 150 PSI, they maintain roughly the same compression rate throughout the cycle. This means that your concentrators are working at their full flow rate, even when they’re pushing against the back-pressure in the tank. The Mighty Mite is a custom 2-stage Thomas compressor. The MAX is a large 2-stage Gast compressor.  

*Unless the system is under warranty, in which case there is no cost.

Q – Will the HVO System operate in a location that is not air-conditioned or heated?

A – Our oxygen compression systems should be operated in an environment that maintains the temperature between 45 F (7.2 C) to 100 F (37.8 C). 

Q -- I have a question not answered in the FAQ. Whom do I contact?

How do HVO systems work?

The HVO oxygen-generating system is similar to a rechargeable battery. The difference is that this battery recharges itself automatically:

  • When the system turns on for the first time, the tank pressure is at 0 PSI. This triggers the “charging” process.

  • Charging consists of running the oxygen concentrators that are attached to the HVO system, compressing the generated oxygen, and storing it in an oxygen-clean tank.

  • Tank pressure is monitored continuously. When the pressure reaches the high threshold (100 PSI for the Standard, 150 PSI for the Mighty Mite and MAX), the system goes into “discharging” mode, at which point the oxygen concentrators and the compressor are turned off. All that can be heard is the quiet hiss of oxygen running through the regulator.

  • Once the pressure drops below the low threshold (30 PSI for the Standard, 100 PSI for the Mighty Mite and MAX), the charging process is triggered again.

If the oxygen generating capacity is well-matched to the output requirements, you’ll receive a continuous supply of oxygen.

HVO supports a wide range of solution scales, from small to very large

Our simplest, lowest-cost system has the following components:

  • (1) Master headbox on a 20-gallon tank

  • (1) 10-LPM PSA Oxygen Concentrator

  • (1) Relay Box

On the other end of the spectrum, here’s a diagram of a very large system with a Master & Drone controlling twelve 10-LPM oxygen concentrators:


The photo below shows a system that has all of the components in the HVO product line. Keep in mind that small systems don’t require a Drone or extra storage tanks.

Screen Shot 2018-10-11 at 2.43.29 PM.png

A: Master Headbox: Controls the overall system
B: Drone Headbox: Augments the oxygen storage capacity. Is controlled by the Master.
C: Storage Tank: Stores oxygen at up to 150 PSI
D: Relay Box: Electrical outlets controlled by the Master
E: Oxygen Concentrators: Separate oxygen from air. Each is plugged into a relay box. The system may have one or more
F: Oxygen Regulator: Controls the oxygen output pressure

Note: Coaxial cables are used to send a control signal from the Master to the other controlled components (Drones, Relay Boxes).

The system shown has ten Philips Respironics M10 (10-LPM) concentrators, yielding 100 LPM of oxygen or the equivalent of a K-tank per hour.

The Master Headbox

The Master Headbox contains a proprietary circuit board that acts as the brain of the system. It may also contain the Seeing Eye™ IoT controller, which stores system metrics (e.g. PSI, purity) in the cloud. See below for more information.

The Deluxe model contains an oxygen purity sensor and an LCD display on the front of the box. The LCD displays system status information such as current PSI and percent full. In addition, there are three LEDs: red for low oxygen purity, green for normal oxygen purity, and blue to indicate low tank pressure.

Of course, every system contains a compressor that takes inbound oxygen and stores it in the tank. The compressor varies with the HVO model. See the post entitled ”How to choose the right HVO model”.

The Drone Headbox

The purpose of a Drone is to increase the number of oxygen concentrators that can be attached to a single system, as well as to increase the volume of oxygen that can be stored. The Drone lacks a controller. It is turned on and off by the Master via the coaxial control signal. Thus, you can’t use a Drone without a Master. The drone also contains a compressor that takes inbound oxygen and stores it in the tank.

The Storage Tank

Storage tanks come in multiple sizes. You should match the number of oxygen concentrators to the tank size as follows:

  • 20-gallon: 1 - 3 oxygen concentrators

  • 30-gallon: 2 - 4 oxygen concentrators

  • 60-gallon: 3 - 5 oxygen concentrators

  • 80-gallon: 4 - 5 oxygen concentrators

When there is overlap, consider whether growth is likely, i.e. whether you will add more oxygen concentrators in the future.

HVO storage tanks are oxygen-rated, meaning that they are designed to store oxygen safely.

Storage Tank Interconnection

Storage tanks may be interconnected to expand storage:

The photo below shows a Master (left), Drone (center), and additional storage (right).

 A Master connected to a Drone, connected to a Storage Tank for 180 Gallons overall

A Master connected to a Drone, connected to a Storage Tank for 180 Gallons overall

The interconnection hoses are braided-steel lines (circled in red in the photo). Together, the interconnected tanks form a single storage unit with a common tank pressure. Expansion is theoretically unlimited.

The Relay Boxes

Relay Boxes come in two sizes:

  • 3-outlet Relay Box: Can power up to three oxygen concentrators. Requires a 20-amp dedicated circuit.

  • 5-outlet Relay Box: Can power up to five oxygen concentrators. Requires a 30-amp dedicated circuit.

 3-outlet and 5-outlet Relay Boxes

3-outlet and 5-outlet Relay Boxes

How it works:

When the master senses low pressure, it generates a 24 volt signal that is sent over the coaxial cable. Once the relay box receives the 24 volt signal, an internal relay switch turns on, causing the power outlets to become energized. There are two coaxial connectors per relay box so you can “daisy chain” the signal to additional components, such as a drone or another relay box.

The Oxygen Concentrator

The HVO System can accommodate most manufacturers 5-10 LPM oxygen concentrators. We carry the following products:

  • Philips Respironics M10, 10 LPM / 9 PSI

  • Airsep Newlife Intensity, 10 LPM / 20 PSI

Use this formula to calculate the number of oxygen concentrators needed:

  • Determine the required sustainable flow rate* in LPM

  • Add 5 to that number and divide by the LPM rating of the oxygen concentrators you plan to recommend

  • Round up.

For example, to maintain a flow of 30 LPM with Airsep Newlife Intensity concentrators, which produce 10 LPM each:

(30 + 5) / 10 LPM = 35 / 10 = 3.5 rounded up = 4

Four oxygen concentrators are needed, and at least a 30-gallon storage tank (see the Storage Tank section).

* The oxygen flow in LPM that the system should be able to deliver continuously.

The Oxygen Regulator

Most oxygen regulators are designed for high-pressure tanks. The regulator below is the Harris Low-Pressure, High-Flow Oxygen Regulator. It was designed for the low pressure that we maintain in the HVO System. This is a critical component that will prevent oxygen flow issues. The cost is less than $200.

Screen Shot 2018-10-11 at 3.09.45 PM.png

Planning for Power

HVO Systems run on standard 110 volt AC power. A household outlet is required for each headbox (either Master or Drone). In addition, a dedicated circuit is required for each Relay Box:

  • Three outlet Relay Box requires 20 amps

  • Five outlet Relay Box requires 30 amps

The HVO Return on Investment Calculator provides an estimate of your HVO system’s power cost, but local power costs should be taken into account for accuracy. Small systems commonly cost less than $1 per day for power.

The Seeing Eye™ Internet of Things (IoT) Cloud Service

IoT is simply computers incorporated into everyday devices, such as thermostats, refrigerators, doorknobs, and, now, HVO systems. The goal is to make these “things” more useful.

What do these computers do?

Mainly, they interact with sensors to gather actionable data and store it in a database in the cloud. HVO’s Seeing Eye™ IoT service is able to measure the pressure in the storage tank, the purity of generated oxygen, headbox temperature and humidity, as well as atmospheric pressure. See the graph below.

Screen Shot 2018-10-11 at 3.25.11 PM.png

A monitor process in the cloud examines the data to see if recent measurements are outside of normal ranges. When a problem is detected, the monitor process notifies a list of interested parties via text, email, or both.

Benefits of the Seeing Eye Cloud Service:

  • Enables customers and support personnel to know instantly about a problem with the oxygen supply, before it becomes a serious issue.

  • Provides a historical record of oxygen availability and purity.

  • Highlights system over- and underutilization.

  • Tracks usage to indicate when a system upgrade may be needed, such as a drone, storage tank, or additional oxygen concentrators.

The HVO Seeing Eye™ website has been certified by Qualsys SSL Labs as an A+ rated secure website.

How to choose the right HVO model

The HVO product line has three models known as the Standard, the Mighty Mite, and the MAX. In this post, you'll learn the difference between them and how to decide which one is best for your application.

The fundamental difference between the models is the compressor:

  • The Standard maintains tank pressure between 30 and 100 PSI. It can accept up to 45 LPM of input volume and requires a minimum input of 10 LPM.

  • The Mighty Mite maintains tank pressure between 100 and 150 PSI. It can accept up to 45 LPM of input volume and requires a minimum input of 20 LPM.

  • The MAX also keeps the tank pressure between 100 and 150 PSI. It can accept up to 55 LPM of input volume and requires a minimum of 40 LPM.

The input volume is the combined gas volume produced by the oxygen concentrators connected to the HVO system.  Oxygen concentrators typically produce 5, 8 or 10 LPM each. The concentrators we recommend using with HVO systems are 10 LPM.

Here’s a list of important questions:

  • What is the required oxygen flow rate? You should know the average flow rate you require in Liters per Minute (LPM). Take that number and add 5, then divide by the LPM  output rating of the oxygen concentrators you plan to purchase and round up. Now you know the number of oxygen concentrators you’ll need. 
    For example, if the flow rate needed is 20 LPM, add 5 to get 25 LPM. Divide by 10 LPM which yields 2.5 rounded up equals 3. You should buy (3) 10 LPM oxygen concentrators.

  • How consistent is your oxygen usage throughout the day? For inconsistent usage (the typical case) you'll want a larger or extra storage tank and one or more extra oxygen concentrators to handle peak usage periods. If usage is consistent, you can use the number you calculated above.

  • How likely is it that your overall oxygen usage will grow over time? If it's very likely, choose a system that has some "headroom", meaning you can add oxygen concentrators. For example, you may choose a 5-outlet relay box instead of the 3-outlet model. If there’s uncertainty, keep in mind that the HVO system is modular and expandable, so you can start small and add components as your requirements become better known.

  • What is the output pressure requirement? If you are a veterinarian running oxygen cages, you probably need at least 50 PSI. This would eliminate the Standard as an option since the tank pressure with this model will go down to 30 PSI, whereas the minimum pressure for the Mighty Mite and MAX is 100 PSI.

Remember that the larger the tank size and the higher the maximum tank pressure, the more stored oxygen will be available to handle peak usage. You can see exactly how much oxygen is stored for the various pressures and tank sizes in the General Questions post.

Here are some example cases:

Example 1: Small
You need 15 LPM of sustainable flow and an output pressure of 30 PSI. Consumption doesn't vary much throughout the workday. In this case, a Standard with two 10 LPM oxygen concentrators will satisfy your immediate requirements.

Example 2: Medium
You need 30 LPM of sustainable flow most of the time, with occasional peak usage of 50 LPM. In this case, a Mighty Mite with four 10 LPM oxygen concentrators will be a good fit. The higher pressure of the Mighty Mite will allow more oxygen to be stored to handle peak usage periods.

Example 3: Large
You need 50 LPM of sustainable flow with peak usage of 80 LPM. The MAX will be your best choice here, as you'll be able to attach six 10 LPM oxygen concentrators. Another way to grow an HVO system is by adding drones and/or storage tanks. For more information, see the post “How to expand your HVO system”.

How to expand your HVO system

If you find that your oxygen requirements have grown since your original purchase or you’re thinking about buying a large HVO system, this post will be helpful.

Did you know that HVO has the only expandable oxygen-generating system on the market? This means that you can start with a system that has one oxygen concentrator generating 10 LPM and add capacity to generate 80, 100, 120 LPM, or even more. Because of this, you can preserve your original investment, making the Total Cost of Ownership (TCO) for an HVO system lower than any competing product on the market today.

There are three ways to expand an HVO system:

  1. Add Oxygen Concentrators

  2. Add a Drone, Storage Tank & Concentrators

  3. Add a Storage Tank

Add Oxygen Concentrators
The least costly option is to add concentrators. However, there is a limit to how much input volume each product can handle. For the Standard and Mighty Mite, you can attach up to five 10 LPM oxygen concentrators, whereas the MAX can handle six. If an existing system has fewer than the maximum number of oxygen concentrators, you can add one or more to increase your HVO system’s overall oxygen-generating capacity.

Add a Drone, Storage Tank & Concentrators
If your system already has the maximum number of oxygen concentrators attached, the next option is to add a Drone. A Drone is a compressor that sits atop its own storage tank and is attached to a set of oxygen concentrators. The Master storage tank is connected to the Drone’s tank via a braided-steel interconnect line that essentially turns two tanks into one big tank. The Drone is turned on and off by the Master via the same coaxial control line that turns the oxygen concentrators on and off.

With a Drone, you get to add both oxygen concentrators and oxygen storage, greatly increasing the overall generating capacity of your system. Drones are available with 60- and 80-gallon tanks. You can add multiple drones, for very large systems.

Add a Storage Tank
If you have peak usage intervals and long periods of low usage, you may be a good candidate for this second-to-lowest-cost option. Adding a storage tank may make it possible to generate and store enough oxygen to perform certain time-bound tasks. In this scenario, you’ll have predetermined the amount of oxygen needed. With the proper-sized storage tank, enough stored oxygen will be available to get the job done. You can always add a Drone headbox to the storage tank at a later date.