How do HVO systems work?

The HVO oxygen-generating system turns itself on and off automatically based on the pressure in the oxygen storage tank. It endeavors to keep the pressure within a range of “setpoints”. Here’s how it works:

  • When the system turns on for the first time, the tank pressure is at zero 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 Pro Series™ contains an onboard ultrasonic oxygen purity sensor and a data display on the front of the box. The display shows 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. There are three compressor models offered, and each has slightly different capabilities. 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 of storage 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


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

If you know your usage in liters per minute (LPM), you can use this formula to calculate the number of oxygen concentrators needed for continuous output:

  • Determine the constant 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).

This formula works best for Veterinary or Aquaculture Systems where the output is more-or-less continuous. For other applications, the typical and peak usage may vary. We are more than happy to make recommendations that will suit your usage and needs. If you have questions, don’t hesitate to contact us.

* 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. We recommend a Harris Low-Pressure, High-Flow Oxygen Regulator, which is designed for the low pressure that is maintained in the HVO tank. This is a critical component that will prevent oxygen flow issues.

Planning for Power

HVO Systems run on standard 110 volt AC power. A household outlet (20 amp dedicated circuit with no other appliances running on it) 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

See the FAQ for information about calculating your power cost.

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.

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