Booster Compressors for Pressure Amplification

Boosters are secondary pressurization equipment in compressed air systems, function is boosting existing compressed air further to higher pressure. When factory main network pressure can't meet certain special process needs, boosters offer an economical solution.

System Integration

Booster Position in Air Network

Position in the System

Boosters aren't standalone, they must be in series after regular pressure compressed air systems.

Typical setup goes like this: air compressor makes 7 bar compressed air, buffered through receiver, dried through dryer, particles removed through filters, enters main network for regular use points. High pressure use points branch from main network into booster, boosted to 30 bar or higher then into high pressure receiver, then to blow molders, leak test stations and other high pressure equipment.

This layout means boosters depend on upstream systems. Regular pressure system has problems, booster side immediately affected.

System Connection Requirements

Inlet pressure should be stable at 6-10 bar range, that's design inlet range for most piston-type boosters. Pressure swing controlled within plus/minus 1 bar is ideal; Atlas Copco, Ingersoll Rand and other makers have explicit specs on this in product manuals. Upstream supply capacity should have margin, recommend about 1.2 times booster's max air consumption, otherwise shortage easily happens during peak use. Inlet must be dried and filtered, non-negotiable.

So boosters usually need pressure regulators and pre-stage receivers upstream to smooth pressure swings, plus precision filter to catch particles and oil mist. Some users figure main network already has filters so boosters don't need another one. That thinking is flawed; there's still piping between main network filters and boosters, rust and weld slag accumulated in pipes still gets into the booster.

Booster Operating Principles

Market boosters divide into three types by principle.

Most Common

Piston-Type

No Electricity

Pneumatic

Emerging

Screw-Type

Piston-type boosters most commonly used. Compressed air enters first stage cylinder for compression, exits into second stage for more compression. Depending on target pressure can be two-stage or three-stage series. Domestic makers like Kaishan, Fusheng, Hongwuhuan all have mature lines. These machines have mature structure, parts easy to find, maintenance workers generally know how to fix. Downsides are vibration and noise are significant; foundations need to be done right or floors shake.

Pneumatic boosters work on different principle, use area differential for pressure multiplication. Big diameter piston connected to small diameter piston; compressed air pushes big piston, small piston end outputs higher pressure, multiplication ratio equals area ratio of two pistons. No electricity needed, runs entirely on air, used more in explosion-proof areas, outdoor sites, on ships. Flow is limited.

Screw-type boosters some makers have been doing in recent years. Principle similar to regular screw compressors except they draw compressed air not atmosphere. Single-stage boost ratio usually 2-3 times. Runs smooth, low noise, worth considering where installation environment has requirements.

Boost Ratio and Flow Relationship

Boost ratio defined as discharge pressure divided by inlet pressure. Inlet 7 bar, discharge 35 bar, boost ratio is 5.

Another way to understand: to stably supply 1 cubic meter per minute of 35 bar high pressure air, upstream regular pressure system needs 5-6 cubic meters per minute surplus capacity. This math must be clear when selecting; otherwise install it then discover regular pressure system can't handle it and have to go back and retrofit.

Common Specs

Pneumatic boost pumps are compact, some palm-sized, work with 4-8 bar inlet, output up to around 40 bar max. Flow from tens to hundreds of liters per minute depending on drive pressure and pump spec. Haskel and Maximator do these well, plenty of domestic brands too. Good for small flow, intermittent high pressure needs like valve testing, pneumatic wrench boosting, lab air.

Medium spec piston-type boosters, inlet 6-10 bar, discharge 30-45 bar, flow calculated at inlet in 1-10 cubic meters per minute range. PET blow molding plants use lots, leak testing lines common too. Kaishan's KB series, Fusheng's FA series have matching models.

Going up, high flow high pressure boosters can hit 40 bar or even above 100 bar discharge, flows of tens of cubic meters per minute. Mining equipment, big blow molding lines, high pressure waterjet cutting use this level.

Selection Guide

Booster vs Dedicated Machine

Comparison with Dedicated High Pressure Machines

Both boosters and dedicated high pressure compressors supply high pressure air; how to choose?

Boosters leverage existing regular pressure system, essentially upgrading on the base. Equipment investment lower, footprint smaller too, often just find a corner to install. Dedicated high pressure machines are independent systems needing complete setup from intake, compression, post-treatment to storage. Machine room, infrastructure, electrical capacity all need to keep up, much higher upfront investment.

Energy wise, boosters go through two compression steps, overall uses more electricity than dedicated machine compressing in one shot. When high pressure volume is small this difference isn't obvious; volume goes up and it's real money.

Supporting Equipment

High pressure receivers installed after booster discharge, buffer pressure pulses and store high pressure air. Capacity depends on usage pattern; intermittent use needs bigger tanks. GB 150 has detailed regs on pressure vessels; high pressure receivers are Category III vessels, design, manufacturing, inspection, registration all need completing.

If high pressure air has dew point requirements, need dedicated high pressure dryers. Regular pressure dryers can't handle high pressure; using them as substitutes causes problems. Not many domestic makers do high pressure adsorption dryers; imported brands mainly SPX and Parker.

High pressure filters, high pressure safety valves must be selected with matching pressure ratings. Safety valve set pressure per TSG 21, usually 1.05-1.1 times max working pressure.

High pressure piping usually stainless or copper tubing, connected via compression fittings or welding. Thread connections have poor sealing reliability in high pressure, not recommended. Leaving some margin on pressure rating is prudent.

Installation Notes

Install boosters as close to high pressure use points as possible; shorter high pressure piping is better. First reduces pressure drop; second shorter piping means fewer leak points and smaller safety hazards. Make sure there's ventilation; piston-type boosters generate real heat. Leave maintenance space around; changing a valve plate or tightening a bolt needs room to stand and put tools.

Avoid sharp bends in high pressure piping layout; put drains at low points. Condensate in high pressure air needs somewhere to go; otherwise it sits in pipes and might freeze and block in winter.