Guide

Compressed Air and Cooling Requirements for a PET Blowing Line

Separate blowing air, service air and cooling duties, and distinguish a pressure-volume calculation from measured compressor and chiller demand.

Direct answer

Compressed Air and Cooling Requirements for a PET Blowing Line: key points

List blowing-air, service-air and cooling requirements separately for the selected machine. Request operating pressure, peak and average flow, air quality, water temperature, flow and heat load at defined connection points. A bottle-volume and absolute-pressure-ratio calculation estimates the gas inventory under simplified assumptions; losses, recovery and operating conditions must be accounted for before selecting a compressor.

Distinguish pressure requirements and connection points before deciding whether supplies can be shared.
Record whether air flow is stated at free-air, normal or operating conditions; figures with different reference conditions cannot be compared directly.
Separate gas inventory from fresh-air consumption, and ask whether quoted consumption includes air recovery and service-air demand.
Investigate cooling with measured supply and return temperatures and flow; bottle deformation or longer cycles are clues, not proof of an undersized chiller.

Review status

What this page is reviewed against.

ClusterBlow machine selection

Last reviewed2026-07-15

Use this page forShortlisting, RFQ preparation and evidence-aware route selection

Factory and route evidence

Public references linked to this buying decision.

These links point to public route pages, reference media or downloadable worksheets that buyers can review before requesting a project-confirmed quote.

How many cavities do I need Cavity count and output set both utility loads. Bottle blow mold design checklist Cooling channel layout is decided in mold design. Machine-only vs machine plus mold RFQ Whether utilities fall inside or outside the supplied scope.

Decision table

Use this guide to avoid vague machine or mold quotes.

Each row converts a common buying question into the exact data engineering needs before final route selection.

Blowing air	Request the required pressure at the machine inlet and identify whether it is gauge or absolute pressure
Blowing air temperature	Record the specified inlet temperature and the reference temperature used for flow reporting
Service air	List pneumatic consumers and their pressure and flow requirements separately from the blowing cycle
Air quality	Dried and filtered; blowing air contacts the inside of the container, so treatment class belongs in the RFQ
Mold cooling water	Obtain permitted supply temperature, flow and return conditions for the mold and process
Cooling connections	Confirm channel and connection dimensions from the mold drawing; no minimum diameter is assumed here
Supply and return pressure	Measure pressure drop and flow across the circuit and investigate restrictions within the equipment limits
Separate cooling duties	List mold, machine and any oil-cooling duties with their temperature and load requirements before combining circuits
Simplified gas inventory	Equivalent reference volume = bottle volume * bottle absolute pressure / reference absolute pressure, assuming equal temperatures
Consumption adjustments	Account for circuit volume, initial gas inventory, leakage, air recovery and actual cycles; do not add the entire exhausted bottle inventory twice
Symptom of under-sized air	Incomplete corners, inconsistent wall distribution and pressure sag when all cavities blow together
Symptom of under-sized cooling	Rising cycle time, soft or deforming bottles on discharge, and shrinkage that drifts over a shift
RFQ-only confirmation	Compressor and chiller capacity, air receiver volume, connection sizes and installed electrical load are confirmed by engineering against your bottle and output data

Workflow

Prepare the buyer-side data package.

01 Step 1

Identify the bottle, process, machine configuration and production schedule before collecting utility requirements.

02 Step 2

If calculating gas inventory, use absolute pressure and explicit reference conditions. Obtain fresh-air consumption separately rather than treating inventory as a demand floor.

03 Step 3

List each air and cooling duty with its connection, pressure, flow and temperature requirements before deciding how the factory will supply it.

04 Step 4

Send bottle volume, target output, ambient temperature and available utility supply so engineering can confirm compressor and chiller capacity against the real line.

FAQ

Questions this guide answers.

What air pressure does a PET blow molding machine need?

Use the pressure specified for the actual machine, bottle and process. Record the inlet measurement point and distinguish gauge pressure from absolute pressure; the gas-inventory equation requires absolute pressure.

How do I estimate compressed air consumption?

At equal temperatures, bottle volume times the absolute pressure ratio gives an equivalent reference gas inventory. To estimate fresh supply, account for initial inventory, circuit volumes, leakage and recovery, then use actual cycles per hour. Request measured or supplier-confirmed consumption at stated reference conditions.

What chilled water temperature does mold cooling need?

Obtain the permitted temperature and flow from the mold and process specification. Check supply and return measurements together; temperature, flow and heat load all matter, and no fixed water temperature or channel diameter is suitable for every route.

Can one compressor run the whole line?

That depends on the required pressures, flows, treatment and supply design. List each consumer first, including downstream equipment, then have the utility supplier evaluate shared or separate supplies rather than assuming a particular compressor arrangement.

How would I know the utilities are under-sized?

Record air pressure and flow during simultaneous blowing, and cooling flow and temperatures during sustained running. Compare them with the machine requirements. Unfilled corners or deforming bottles also have process and tooling causes, so symptoms alone do not establish utility capacity.