Buyer-Supplied vs Vendor-Supplied Chiller

Water-cooled electromagnets and high-current coil systems usually need more than a magnet and a power supply.

They also need a cooling solution that can remove heat safely and consistently.

That creates one practical procurement question:

Should the buyer provide the chiller locally, or should the magnet vendor supply the chiller as part of the system?

Both options can work.

A buyer-supplied chiller may reduce freight cost, simplify local service, and match existing facility standards.

A vendor-supplied chiller may reduce integration risk, simplify responsibility, and make factory testing easier.

The wrong responsibility split, however, can create problems after delivery:

The magnet overheats.
cooling flow is too low.
inlet water temperature is too high.
fittings do not match.
the chiller trips during operation.
condensation appears.
cooling interlocks are not wired.
supplier and buyer disagree about responsibility.
FAT and SAT results do not match.

For water-cooled electromagnets, Helmholtz coil systems, high-current coil drivers, and custom Magnet & Field Systems, the chiller should not be treated as an afterthought.

It is part of the operating system.

1. Why Chiller Responsibility Matters

A water-cooled magnet project involves several connected items:

Magnet coils
cooling channels
hoses
fittings
chiller or facility water
flow rate
pressure
inlet temperature
water quality
flow interlock
temperature protection
power supply duty cycle
test conditions
warranty boundary

If one party supplies the magnet and another party supplies the chiller, the interface must be defined clearly.

Otherwise, a failure may lead to a difficult question:

Was the issue caused by the magnet, the chiller, the installation, the site water, the flow setting, or the operating duty cycle?

This is why the responsibility split should be decided before PO, not after delivery.

2. Why Water Cooling Is Needed in Some Magnet Systems

Electromagnets and coil systems generate heat when current flows through the windings.

Higher field, higher current, longer duty cycle, and compact coil design can all increase thermal load.

Water cooling is often used when the system requires:

High continuous field
high current
long operating time
repeatable duty cycles
better thermal stability
compact magnet geometry
reduced cooldown time
lower coil temperature
improved reliability

A documented GMW electromagnet manual specifies cooling-water temperature, flow, pressure, filtration, water quality, flow-interlock considerations, and dew-point warnings for a laboratory electromagnet. It also notes that air cooling may not be suitable where high field stability is required because coil temperature variation can cause dimensional changes.

That is the practical lesson:

Cooling is not only about preventing damage. It also affects field stability, repeatability, and system reliability.

3. Buyer-Supplied Chiller: What It Means

A buyer-supplied chiller means the customer provides the cooling equipment locally.

The vendor supplies the magnet, coil system, power supply, and technical cooling requirements.

The buyer provides:

Chiller
local hoses or adapters
cooling fluid
local electrical power for chiller
site installation
maintenance
filters
spare parts
local service support

This option can work well when the buyer has strong facilities support or already uses standard laboratory chillers.

4. Vendor-Supplied Chiller: What It Means

A vendor-supplied chiller means the magnet supplier provides the chiller as part of the package.

The vendor may select a chiller based on:

Magnet heat load
required flow rate
required pressure
inlet temperature range
duty cycle
power supply heat load, if cooled
hose interface
interlock requirements
FAT conditions
installation plan

This option can reduce integration uncertainty because the cooling package is selected together with the magnet system.

However, it may also increase freight cost, customs complexity, lead time, and local service concerns.

5. The Chiller Is Not a Generic Accessory

A chiller must be matched to the magnet’s actual thermal requirement.

Important parameters include:

Cooling capacity
flow rate
pressure
temperature stability
setpoint range
reservoir size
pump capacity
fluid compatibility
hose connection
power input
noise level
footprint
heat exhaust
alarm output
flow interlock interface
maintenance needs

A small lab chiller may look suitable but fail under continuous high-current operation.

A large industrial chiller may provide enough cooling but be oversized, noisy, expensive, and difficult to integrate.

The correct choice depends on the full operating condition.

6. Cooling Capacity Must Match Real Heat Load

The cooling capacity should be selected based on the expected heat generated during operation.

For a water-cooled electromagnet, heat load depends on:

Coil current
coil resistance
duty cycle
continuous operating time
ambient temperature
cooling-water temperature
power supply configuration
whether the chiller also cools other devices

A chiller that works for short tests may not work for eight-hour continuous operation.

A chiller that works at 20°C ambient may struggle in a 35°C equipment room.

The buyer should not choose a chiller only by nameplate power.

The supplier should provide required cooling capacity under the agreed operating duty.

7. Flow Rate Is Not Optional

Cooling capacity alone is not enough.

The cooling fluid must actually flow through the magnet at the required rate.

Low flow may cause:

Coil overheating
thermal drift
hot spots
unstable field
flow interlock trips
reduced service life
warranty disputes

The GMW electromagnet manual provides a specific example of clean cooling water at 2 L/min and 0.5 bar for its model, and recommends a filter before the magnet input to avoid particulate blockage and unreliable operation of a water-flow switch.

The exact values will differ by system, but the principle is universal:

Flow rate must be specified, measured, and protected.

8. Pressure and Pressure Drop Must Be Checked

A chiller pump must overcome the pressure drop of:

Magnet cooling channels
hoses
fittings
filters
valves
quick connectors
flow meters
heat exchangers

If the chiller cannot provide enough pressure at the required flow, the system may not cool properly.

A buyer-supplied chiller should therefore be checked against:

Required minimum flow
required pressure
maximum allowed pressure
pressure drop through the magnet
hose length
fitting restrictions
filter condition
chiller pump curve

A chiller may have a strong cooling compressor but a weak pump.

That mismatch can cause real problems.

9. Inlet Water Temperature Matters

The magnet supplier may specify required inlet temperature.

If the inlet water is too warm:

coil temperature rises
thermal margin decreases
continuous-duty field may be reduced
stabilization time increases
protection may trip earlier
field drift may increase

If the inlet water is too cold:

condensation risk may increase
electrical leakage risk may increase
corrosion risk may increase
water may drip onto sensitive equipment

The GMW manual warns against cooling the magnet below the ambient dew point because condensation may cause electrical shorts and corrosion.

A chiller setpoint should therefore be chosen carefully.

Lower temperature is not automatically better.

10. Water Quality Is a Responsibility Issue

Cooling fluid quality affects long-term reliability.

Possible water-quality problems include:

Scale
corrosion
algae
bacterial growth
particles
high conductivity
blocked filters
clogged cooling channels
galvanic corrosion
leakage current

The GMW manual recommends distilled or deionized water with a biocide for recirculating cooling systems and warns that some corrosion inhibitors can increase water conductivity, leakage currents, and electrochemical corrosion.

For buyer-supplied chillers, water-quality responsibility must be clear.

The buyer should ask:

What fluid should be used?
Is deionized water required?
Is glycol allowed?
Is biocide required?
Are corrosion inhibitors allowed?
What filtration is required?
How often should water be replaced?
Who is responsible for water-related damage?

These details should be written down.

11. Flow Interlock Should Be Defined Before Delivery

A flow interlock protects the magnet by preventing operation when cooling flow is inadequate.

It may involve:

Flow switch
flow sensor
chiller alarm relay
power supply inhibit
controller input
software alarm
emergency shutdown logic

The Trane commercial HVAC guidance explains the concept of flow proving and flow interlocks, including the use of flow-proving devices and pump-starter contacts in chilled-water systems.

For magnet systems, the principle is practical:

The magnet should not rely only on operator memory to confirm cooling flow.

12. Buyer-Supplied Chiller: Advantages

A buyer-supplied chiller can be a good choice when the laboratory has suitable infrastructure.

Advantage 1: Local Availability

The buyer can purchase from a local brand with local voltage, plugs, language, and service support.

Advantage 2: Lower Freight Cost

A chiller can be heavy and bulky. Buying locally may reduce international freight, import duty, and customs work.

Advantage 3: Faster Local Maintenance

Local technicians can service the chiller without overseas coordination.

Advantage 4: Facility Standardization

Some universities or companies require all chillers to match approved brands or facility standards.

Advantage 5: Easier Replacement

If the chiller fails, the buyer may replace it locally without waiting for international shipment.

Buyer-supplied cooling is often practical for experienced laboratories.

13. Buyer-Supplied Chiller: Risks

The risks are also real.

Risk 1: Wrong Capacity

The buyer may select a chiller that cannot remove the required heat.

Risk 2: Wrong Flow or Pressure

The chiller may not meet the required flow through the magnet.

Risk 3: Wrong Fittings

Hose size, thread type, quick connectors, or adapters may not match.

Risk 4: No Interlock Integration

The chiller may run independently without providing a flow or fault signal to the magnet system.

Risk 5: Water Quality Problems

Local fluid choices may not match the magnet’s requirement.

Risk 6: Unclear Warranty Boundary

If overheating occurs, supplier and buyer may disagree about whether the chiller was suitable.

Buyer-supplied chillers work best when the supplier provides clear cooling specifications and the buyer confirms compliance before purchase.

14. Vendor-Supplied Chiller: Advantages

A vendor-supplied chiller can reduce integration uncertainty.

Advantage 1: Matched Selection

The supplier can select the chiller based on magnet design, duty cycle, and cooling requirement.

Advantage 2: Easier FAT

The supplier can test the magnet and chiller together before shipment.

Advantage 3: Clearer Responsibility

If the magnet, chiller, hoses, and interlocks are supplied as a system, troubleshooting responsibility is easier to define.

Advantage 4: Matched Interfaces

Hoses, fittings, electrical signals, and alarm contacts can be prepared together.

Advantage 5: Better Documentation

The supplier can provide a unified cooling procedure, interlock diagram, and test record.

Vendor-supplied cooling is often better for high-value, high-duty, or custom systems where performance risk matters more than reducing freight.

15. Vendor-Supplied Chiller: Risks

A vendor-supplied chiller is not always the best choice.

Risk 1: Higher Freight and Import Cost

Chillers can add weight, volume, customs classification, and import cost.

Risk 2: Local Voltage Mismatch

The chiller must match local power standards.

Risk 3: Local Service Difficulty

If a fault occurs, the buyer may need overseas support or replacement parts.

Risk 4: Language and Compliance

Local safety, electrical, or facility requirements may prefer locally approved equipment.

Risk 5: Longer Lead Time

If the chiller is not in stock, it may delay shipment.

Risk 6: Over-Specification

The vendor may choose a conservative chiller that works well but increases cost.

Vendor-supplied cooling is helpful only when the selected chiller fits the buyer’s site and service reality.

16. Facility Water vs. Recirculating Chiller

Some buyers may not need a standalone chiller if facility cooling water is available.

Facility Water Advantages

Existing infrastructure
no separate chiller purchase
reduced equipment footprint
potentially high cooling capacity

Facility Water Risks

Variable temperature
uncertain pressure
water quality issues
shutdown during building maintenance
no dedicated alarm output
possible condensation
unclear responsibility
drainage cost
local regulations

Recirculating Chiller Advantages

Controlled temperature
closed-loop water quality
predictable operation
local alarm output
easier FAT simulation
reduced water consumption

Recirculating Chiller Risks

Additional equipment cost
maintenance
heat exhaust into room
pump noise
possible leaks
local service requirement

The choice depends on site infrastructure and reliability expectations.

17. Who Owns the Cooling Specification?

Even if the buyer supplies the chiller, the magnet supplier should provide minimum cooling requirements.

These should include:

Required cooling capacity
required flow rate
required pressure range
inlet temperature range
water quality requirement
fitting type
hose size
maximum allowable pressure
flow-interlock requirement
recommended chiller margin
duty-cycle basis
cooling conditions used during FAT

The buyer then confirms whether the local chiller meets these requirements.

This is the cleanest responsibility split.

18. Who Owns the Cooling Performance?

This is where disputes often appear.

A fair responsibility model is:

Vendor Responsibility

Magnet design
heat-load estimate
cooling requirement specification
cooling interface definition
interlock interface definition
FAT under stated cooling conditions
documentation of operating limits

Buyer Responsibility

Providing cooling equipment if buyer-supplied
site power
local installation
water quality
maintenance
flow and temperature monitoring
ensuring site operation matches the required conditions

If the vendor supplies the chiller, vendor responsibility expands to include chiller selection and system-level integration.

19. FAT Conditions Must Match the Chiller Plan

Factory Acceptance Testing should state what cooling equipment was used.

Record:

Chiller model
cooling capacity
inlet temperature
outlet temperature
flow rate
pressure
fluid type
ambient temperature
duty cycle
continuous-run duration
thermal interlock status

If the buyer will use a different chiller on site, FAT data should not be interpreted blindly.

The site chiller must be compared with the FAT cooling condition.

20. SAT Should Confirm the Site Cooling System

Site Acceptance Testing should include cooling verification.

Check:

Chiller startup
flow rate
inlet temperature
outlet temperature
pressure
leak condition
alarm contact
flow interlock
overtemperature protection
magnet operation under load
continuous-duty thermal behavior

A magnet that passes FAT with the vendor’s factory chiller may behave differently with a buyer-supplied site chiller.

SAT should close that gap.

21. Interface Drawings Prevent Trouble

Cooling interface drawings should show:

Water inlet
water outlet
fitting size
thread type
hose diameter
flow direction
pressure limit
drain point
filter position
flow switch position
temperature sensor position
chiller alarm wiring
power supply interlock wiring

Do not rely on verbal descriptions like “standard hose connector.”

There is no universal standard in international equipment delivery.

22. Fittings and Adapters Should Be Decided Early

Common interface problems include:

Metric vs. imperial thread
BSP vs. NPT
quick connector mismatch
hose inner diameter mismatch
wrong clamp type
insufficient bend radius
no drain valve
no shutoff valve
no filter access
no leak tray

A simple adapter issue can delay installation for days.

For overseas projects, small fittings should be included or at least specified clearly.

23. Cooling Fluid Compatibility Must Be Confirmed

Possible cooling fluids include:

Distilled water
deionized water
glycol-water mixture
treated facility water
vendor-recommended coolant

Each has trade-offs.

For example:

Deionized water may reduce conductivity but can be chemically aggressive if not managed properly.
Glycol can reduce freezing risk but changes heat capacity and viscosity.
Facility water may be convenient but may contain minerals or contaminants.
Corrosion inhibitors may not be acceptable in some high-quality electrical systems.

The supplier should state acceptable fluids.

The buyer should not substitute fluid without confirming compatibility.

24. Chiller Location Affects Performance

The chiller should be placed where it can operate properly.

Consider:

Distance from magnet
hose length
height difference
airflow clearance
room ventilation
heat exhaust
acoustic noise
floor loading
access for maintenance
drainage
leak containment
power outlet location

Long hoses can increase pressure drop and warm-up.

Poor ventilation can reduce cooling efficiency.

A chiller installed in a cramped corner may not perform like it did during FAT.

25. Heat Rejection Into the Room

A recirculating chiller removes heat from the magnet and rejects it somewhere else.

Often, that heat goes into the room.

This can matter for:

Small laboratories
temperature-sensitive experiments
cryogenic systems
optical alignment
long-duration testing
air-conditioning load
operator comfort

The buyer should ask whether the site can handle the chiller’s heat rejection.

Cooling the magnet may warm the laboratory if the room HVAC is insufficient.

26. Noise and Vibration

Chillers can generate:

Pump noise
compressor noise
fan noise
vibration
water-flow noise

This may matter for:

optical measurements
low-noise Hall measurements
scanning stages
cryogenic experiments
sensitive sensor testing
acoustic-sensitive laboratories

If the magnet system is used near optical tables or vibration-sensitive instruments, chiller placement and hose routing should be planned carefully.

27. Interlock Logic Should Be Written Clearly

A useful cooling interlock definition should answer:

What signal proves flow?
What signal indicates chiller fault?
Does the magnet power supply shut down automatically?
Does the current ramp down or trip immediately?
Is manual reset required?
Is the fault logged?
Can the system start if the chiller is off?
Can the user bypass the interlock?
Who is allowed to bypass it?
Is bypassing recorded?

A flow switch alone is not a complete safety strategy unless its connection to the magnet control system is defined.

28. Buyer-Supplied Chiller with Vendor Interlock: A Good Hybrid

One practical responsibility split is:

Buyer supplies local chiller.
Vendor supplies cooling requirements and interlock input.
Buyer selects local chiller with alarm or flow output.
Vendor confirms signal compatibility.
Site acceptance includes cooling interlock test.

This gives the buyer local serviceability while keeping magnet protection integrated.

It is often a strong compromise.

29. Vendor-Supplied Chiller with Buyer Maintenance

Another possible split is:

Vendor supplies chiller.
Vendor tests magnet and chiller together at FAT.
Buyer maintains chiller locally after delivery.
Buyer follows water-quality and filter schedule.
Vendor supports magnet-side troubleshooting.
Chiller brand support may be local if available.

This can work well if the chiller brand has international service coverage.

30. Avoid the Worst Split: Undefined Responsibility

The worst arrangement is:

Supplier says “buyer provides cooling.”
Buyer buys a chiller based on guesswork.
No one defines flow, pressure, temperature, or interlocks.
FAT uses one cooling setup.
SAT uses another.
Magnet trips or overheats.
Both sides blame the other.

This is preventable.

Cooling responsibility should be a named section in the quotation.

31. What to Ask If the Buyer Supplies the Chiller

Before accepting a buyer-supplied chiller, ask:

What chiller model will be used?
What cooling capacity is available?
What flow rate can it provide at the required pressure?
What is the temperature setpoint range?
What is the expected inlet water temperature?
What fluid will be used?
Are filters included?
Does it have flow or fault output?
What hose and fitting sizes are available?
Who installs it?
Who maintains it?
Can it support continuous operation?
Is the chiller dedicated or shared?

Do not accept “we have a chiller” as a complete answer.

32. What to Ask If the Vendor Supplies the Chiller

If the vendor supplies the chiller, the buyer should ask:

What chiller model is included?
What cooling capacity does it provide?
What voltage and plug are required?
What flow and pressure are provided?
What fluid is recommended?
What maintenance is required?
Are filters included?
Are spare filters included?
Is local service available?
What alarms are available?
Is the chiller integrated with the magnet interlock?
Is the chiller tested during FAT?
Is the chiller included in warranty?
How is it packed for export?

The chiller should be treated as a delivered subsystem, not a loose accessory.

33. Chiller Sizing Should Include Margin

A chiller should not be selected with zero margin.

Useful margins may account for:

Warm ambient conditions
aging performance
filter blockage
longer hoses
higher duty cycle
power supply heat
future field upgrade
site ventilation limits
imperfect maintenance

However, too much oversizing may increase cost, noise, footprint, and temperature-control instability.

The right margin should be practical, not extreme.

34. Continuous Operation Requires Stronger Cooling Evidence

For intermittent testing, basic cooling verification may be enough.

For continuous operation, buyers should request:

Heat-load calculation or estimate
chiller capacity basis
required flow and pressure
continuous-run FAT
coil temperature trend
inlet and outlet temperature data
protection threshold
flow-interlock test
recommended maintenance interval

Continuous operation cannot be proven by a two-minute startup video.

35. Cooling Affects Field Stability

Thermal behavior can affect magnetic performance.

As the coil heats:

Resistance changes
voltage demand changes
mechanical dimensions may shift
temperature gradients may appear
field stability may change
repeatability may be affected

A stable chiller helps reduce thermal variation.

For precision magnetic measurement, cooling should be evaluated not only by “no overheating,” but also by field stability after warm-up.

36. Chiller Failure Mode Should Be Planned

Ask what happens if:

Chiller loses power
pump fails
flow drops
filter clogs
hose leaks
temperature rises
reservoir level is low
alarm cable disconnects
software communication fails
user forgets to turn on chiller

A safe system should move to a defined safe state.

For high-current magnets, uncontrolled cooling failure can become serious quickly.

37. Documentation Checklist

The cooling package documentation should include:

Cooling requirement sheet
chiller model and manual
cooling circuit diagram
fitting specification
hose specification
fluid requirement
flow and pressure requirement
inlet temperature range
maintenance schedule
interlock wiring diagram
alarm logic
FAT cooling data
SAT cooling checklist
troubleshooting guide

If the chiller is buyer-supplied, the supplier should still provide the requirement sheet.

If the chiller is vendor-supplied, the vendor should provide the full documentation package.

38. Better RFQ Language

Instead of writing:

“Please include water cooling.”

write:

“Please specify the cooling requirement for the water-cooled electromagnet, including required chiller capacity, minimum flow rate, pressure range, inlet water temperature, acceptable cooling fluid, filtration, fitting type, flow interlock, overtemperature protection, continuous-duty basis, FAT cooling conditions, and responsibility boundary if the chiller is supplied locally by the buyer.”

For a vendor-supplied package:

“Please quote the electromagnet with a matched recirculating chiller, hoses, fittings, cooling-fluid recommendation, alarm or flow interlock interface, FAT test with cooling data, and documentation for maintenance and site acceptance.”

This language prevents hidden assumptions.

39. Decision Guide: Which Split Works Better?

Choose Buyer-Supplied Chiller When

The buyer has approved local chiller brands.
local service is important.
facility engineers can manage cooling.
import cost must be minimized.
the supplier provides clear cooling requirements.
the buyer can verify flow, pressure, temperature, and water quality.
interlock integration is still defined.

Choose Vendor-Supplied Chiller When

The cooling requirement is demanding.
continuous operation is required.
the buyer wants one integrated system.
FAT must test magnet and cooling together.
responsibility should be simple.
the buyer lacks local cooling expertise.
cooling failure would create high risk.
the vendor can supply a locally compatible chiller.

Choose Facility Water When

The facility water is stable, clean, and available.
pressure and flow meet requirements.
water temperature is controlled.
shutdown risk is low.
interlock and flow monitoring are added.
water quality is acceptable.

Avoid Any Option When

flow is unknown.
pressure is unknown.
water quality is unknown.
no interlock exists.
cooling conditions are not included in FAT or SAT.
responsibility is not written.

40. Common Buyer Mistakes

Mistake 1: Choosing a Chiller Only by Cooling Capacity

Flow and pressure may still be insufficient.

Mistake 2: Ignoring Water Quality

Poor water quality can damage cooling channels over time.

Mistake 3: Forgetting Interlocks

A chiller that cools well during normal operation still needs fault protection.

Mistake 4: Using Different Cooling Conditions for FAT and SAT

Factory and site results may not match if cooling conditions differ.

Mistake 5: Setting Water Too Cold

Cooling below dew point can create condensation risk.

Mistake 6: Assuming Vendor Responsibility When Buyer Supplies Cooling

Responsibility must be defined in writing.

Mistake 7: Ignoring Maintenance

Filters, fluid, pumps, and hoses require attention.

Mistake 8: Treating Chiller Selection as a Purchasing Detail Only

Chiller selection is an engineering decision.

41. How Cryomagtech Supports Chiller Responsibility Planning

Cryomagtech supplies water-cooled electromagnets, Helmholtz coils, high-current coil systems, excitation power supplies, field probes, control software, safety interlocks, and custom Magnet & Field Systems for research and industrial testing.

For cooling-supported magnet projects, we help evaluate:

Buyer-supplied vs. vendor-supplied chiller options
cooling capacity
flow and pressure requirements
inlet temperature range
water quality and filtration
hose and fitting interfaces
flow interlock and alarm logic
continuous-duty thermal behavior
chiller compatibility with power supply and magnet duty
FAT cooling data
SAT cooling checklist
responsibility boundary
maintenance and warranty considerations

👉 Product link placeholder: Cryomagtech Water-Cooled Electromagnet, Coil System, and Chiller Integration Support

The best chiller responsibility split is not always the one with the lowest initial cost.

It is the one that gives the laboratory reliable cooling, clear interfaces, measurable acceptance, practical service support, and a fair warranty boundary.

References

GMW Associates – Model 5403 Electromagnet User Manual
https://gmw.com/wp-content/uploads/2019/03/GMW_MAN_5403-Mar-00.pdf
Trane Commercial HVAC Help Center – Chilled Water Flow Interlock and Flow Switch
https://support.trane.com/hc/en-us/articles/23501030916237-Chilled-Water-Flow-Interlock-and-Flow-Switch
NIST – Metrological Traceability: Frequently Asked Questions and NIST Policy
https://www.nist.gov/metrology/metrological-traceability

Key Takeaways

A water-cooled electromagnet or coil system should not treat the chiller as a generic accessory.
Buyer-supplied chillers can reduce freight cost and improve local serviceability, but they require clear cooling specifications and site verification.
Vendor-supplied chillers reduce integration risk and make FAT easier, but may increase shipping cost, import complexity, and local service concerns.
Cooling capacity, flow rate, pressure, inlet temperature, fluid quality, filtration, fittings, and interlocks must all be defined.
A flow interlock or flow-proving method helps prevent magnet operation under inadequate cooling conditions.
Cooling water set too cold may create condensation risk.
FAT should record cooling conditions, and SAT should confirm that site cooling matches the required operating basis.
The responsibility boundary should be written clearly before PO.
Continuous-duty systems require stronger cooling evidence than short-duty systems.
The best responsibility split depends on site infrastructure, operating duty, service expectations, risk level, and acceptance requirements.

For water-cooled magnet projects, the key question is not only:

“Who buys the chiller?”

The better question is:

“Who is responsible for proving that the cooling system can support the agreed magnetic field, duty cycle, safety interlocks, site conditions, and warranty boundary?”