A Coordinated Electric System Interconnection Review—the utility’s deep-dive on technical and cost impacts of your project.

Challenge: Frequent false tripping using conventional electromechanical relays
Solution: SEL-487E integration with multi-terminal differential protection and dynamic inrush restraint
Result: 90% reduction in false trips, saving over $250,000 in downtime

The three operating regions you have to design to

Device	Output vs voltage	Response	Best suited to	Main limitations
Mechanically switched capacitor or reactor	Proportional to voltage squared	Seconds; discrete steps; limited switching operations per day	Steady-state reactive supply, voltage profile, loss reduction	No dynamic capability; step voltage change on switching; capability collapses when most needed
Static var compensator	Capacitive branches proportional to voltage squared	A few cycles; continuously controllable	Continuous control where cost matters and deep voltage support is not the driver	Square-law capability loss; harmonic filters are part of the plant and interact with the network
STATCOM	Approximately proportional to voltage — constant current capability	One to two cycles closed loop; converter response faster still	Voltage stability margin, weak interconnections, fast disturbance recovery, flicker and unbalance compensation	Higher capital cost; converter losses; adds a converter and its control dynamics to the network
Synchronous condenser	Governed by machine capability and excitation	Excitation response in the hundreds of milliseconds; inherent inertial response instantaneous	System strength and inertia, short-circuit contribution, black start support	Rotating plant with maintenance and losses; slower controlled response than a converter
STATCOM with energy storage	Reactive as a STATCOM, plus real power within the storage rating	As STATCOM for reactive; real power limited by storage	Where a real power deficiency is part of the problem	Cost and complexity of the storage; different failure and maintenance profile

Stage	Keentel scope	Outcome
Screening	Series-compensation proximity, radial contingency review, UIF and short-circuit ratio screening, frequency scans	Early identification of which SSO types apply
Detailed studies	PSCAD/EMTDC EMT studies with vendor real-code models, impedance-based and frequency-scan analysis	Clear evidence of stability margins or risk
Model quality	EMT model review, benchmarking against positive-sequence models, model acceptance support	Models that system operators accept
Mitigation	Control retuning recommendations with vendors, SSDC and bypass logic requirements, protection and monitoring specifications	Practical, coordinated solutions
Interconnection support	SSR and SSO study reports for ISO and utility requirements, response to reviewer comments	Fewer delays in the interconnection process

A coolant distribution unit (CDU) is the heart of a liquid-cooled data center. It sits between the facility water system and the IT cooling loop, transfers heat between them through a heat exchanger, and controls the flow, pressure and temperature of the coolant delivered to the racks. The two fluids never mix.

How heat moves through a CDU, in four steps

Cool coolant enters from the facility. The facility water system (chillers, cooling towers or dry coolers) delivers cool water to the primary side of the CDU.
The CDU manages the flow. A control valve modulates facility water through the plate heat exchanger, while redundant pumps circulate the secondary coolant through filters to the racks at a controlled pressure.
Coolant absorbs the IT heat. Coolant flows through cold plates on processors and accelerators, picks up heat and returns warmer to the CDU.
Heat is rejected to the facility. The heat exchanger transfers that heat to the facility water, which returns to the plant for rejection.

The two loops

Item	Primary circuit — facility water system (FWS)	Secondary circuit — technology cooling system (TCS)
Serves	Chillers, cooling towers or dry coolers	IT racks: cold plates, manifolds, rear-door heat exchangers
Typical fluid	Treated facility water	Propylene glycol 25% (PG25) or treated water
Controlled by	Facility plant, and the CDU's modulating valve	CDU pumps, valves and controls
Key measurements	Supply and return temperature, flow, valve position	Supply and return temperature, flow, differential pressure, system pressure
Cleanliness	Facility water quality programme	Tight filtration, often 50 µm or finer, and fluid chemistry monitoring

Component	Function
Plate heat exchanger	Transfers heat between the loops while keeping the fluids separate
Primary control valve	Modulates facility water flow to hold the secondary supply temperature
Main pumps (N+1 or 2N)	Circulate the secondary coolant and set its flow and differential pressure
Filter or strainer	Removes particles that would block cold-plate micro-channels
Expansion tank and fill pump	Maintain secondary system pressure and make up fluid losses
Sensors and controls	Temperature, flow, pressure, leak and fluid-quality monitoring; BMS integration
Drain and fill points	Commissioning, maintenance and fluid replacement

How CDUs work, how to size and check them with real heat balances, and what liquid cooling means for the electrical, mechanical and resilience design of AI and high-density data centers.

Why liquid cooling, and why now

Air cooling works well up to roughly 15–30 kW per rack, depending on containment and airflow design. AI training and inference racks now draw tens to well over 100 kW each, with processors and accelerators that dissipate hundreds of watts to over a kilowatt per chip. Air cannot carry that heat away efficiently: water has about 3,500 times the volumetric heat capacity of air, so a small pipe does the work of a very large duct.

Direct-to-chip (cold-plate) liquid cooling has therefore become the default for high-density AI hardware. The CDU is the device that makes it practical, by delivering clean, temperature-controlled coolant to the racks while connecting to the building's existing or new facility water plant.

The vocabulary: FWS, TCS and approach

ASHRAE TC 9.9 and the Open Compute Project (OCP) use a consistent set of terms:

Facility water system (FWS): the primary loop from the cooling plant to the CDU.
Technology cooling system (TCS): the secondary loop from the CDU to the IT equipment.
Approach temperature difference (ATD): TCS supply temperature minus FWS supply temperature. OCP's liquid-to-liquid CDU test methodology rates capacity at an ATD of 5 °C.

ASHRAE classifies facility water by its maximum supply temperature. All classes have a lower limit of 2 °C:

ASHRAE class	Maximum facility water supply	Typical heat rejection
W17 (formerly W1)	17 °C	Chillers
W27 (formerly W2)	27 °C	Chillers with economisers, cooling towers
W32 (formerly W3)	32 °C	Cooling towers, dry coolers in many climates
W40 (new)	40 °C	Dry coolers, chiller-free in most climates
W45 (formerly W4)	45 °C	Dry coolers; heat reuse becomes practical
W+ (formerly W5)	Above 45 °C	Heat reuse, district heating

Warmer facility water means fewer chiller hours, lower energy use and more free cooling. The limit is set by the IT equipment: the TCS supply temperature the server vendor allows, minus the CDU's approach.

Inside the CDU

The plate heat exchanger

Brazed or gasketed plate heat exchangers provide a large surface area in a compact volume. The two fluids flow counter-current through alternate channels, which allows a close approach temperature. Plate surface patterns create turbulence and improve heat transfer, at the cost of pressure drop. The exchanger is sized for the design heat load, the approach and the allowable pressure drop on both sides, with margin for fouling.

Primary control valve

A modulating valve on the facility side, typically controlled to hold the TCS supply temperature at its setpoint, adjusts how much facility water passes through the exchanger. At low IT load it throttles back; at full load it opens. Valve authority and characteristic matter: an oversized valve operating near closed gives poor control and temperature hunting.

Pumps and pressure control

The CDU's pumps circulate the TCS coolant through the manifolds and cold plates. They are usually variable-speed, controlled on differential pressure across the supply and return headers or on flow. Redundancy of at least N+1 is standard practice, so one pump can fail or be serviced without interrupting flow.

An expansion tank absorbs thermal expansion, and a fill pump maintains system static pressure and makes up small losses. Low pressure can indicate a leak; high pressure can indicate thermal expansion problems or a closed path.

Filtration and fluid quality

Cold plates use fine internal channels and micro-fins, often a few hundred micrometres wide, which can be blocked by debris. OCP's CDU test methodology references a primary filter of 200 µm or finer and a secondary filter of 50 µm or finer. OCP's PG25 guidance recommends fluid filtered at 50 µm or finer before delivery, with 25 µm preferred, and continuous sidestream filtration of a portion of the circulating flow.

Sensors, controls and leak detection

A modern CDU monitors supply and return temperatures on both loops, flow, differential and static pressure, pump status, valve position, filter differential pressure and fluid level. Many also monitor coolant conductivity or quality. Leak detection cable under manifolds and at rack connections, integrated with the building management system, is essential.

The heat balance: every CDU calculation starts here

Heat carried by a liquid stream is:

Measurement	Value
FWS supply / return	9.7 °C / 15.2 °C (ΔT 5.5 K)
FWS flow	70 L/min
TCS supply / return	22.2 °C / 34.6 °C (ΔT 12.4 K)
TCS flow	87 L/min
Primary valve position	87%
TCS differential pressure	1.02 bar
TCS system pressure	0.58 bar

TCS side (PG25, ρ ≈ 1.02 kg/L, c_p ≈ 3.93 kJ/kg·K): 87 ÷ 60 × 1.02 × 3.93 × 12.4 ≈ 72 kW.

FWS side (water, ρ ≈ 1.00 kg/L, c_p ≈ 4.18 kJ/kg·K): 70 ÷ 60 × 1.00 × 4.18 × 5.5 ≈ 27 kW.

The two sides differ by a factor of about 2.7, which is physically impossible in steady state. Either a measurement is wrong or the plant is not in steady state. To carry 72 kW, the facility side needs either about 189 L/min at a 5.5 K rise, or a rise of about 14.8 K at 70 L/min, which would put the facility return near 24.5 °C rather than 15.2 °C.

This check is one of the most valuable commissioning and troubleshooting tools for liquid cooling. A heat balance that does not close usually points to a faulty flow meter, a mislocated temperature sensor, a bypass flow, or air in the loop.

Two other things in these values deserve attention:

Approach. TCS supply at 22.2 °C with FWS supply at 9.7 °C is a 12.5 K approach. A well-sized CDU typically achieves a few degrees. A large approach with the valve 87% open suggests an undersized or fouled heat exchanger, or reduced FWS flow.
Condensation. Facility water at 9.7 °C is below the dew point of many data hall environments. Exposed FWS piping, valves and the CDU's primary side must be insulated with a vapour barrier, or the facility water temperature raised. ASHRAE guidance for data halls commonly uses a maximum dew point of 15 °C.

A consistent design example: a 1 MW in-row CDU

Parameter	TCS (PG25)	FWS (water)
Heat load	1,000 kW	1,000 kW plus pump heat
Supply temperature	30 °C	25 °C (approach 5 K; ASHRAE W27)
Return temperature	≈ 40 °C	≈ 33 °C
Temperature rise	≈ 10 K	8 K
Flow	1,500 L/min (1.5 L/min per kW)	≈ 1,800 L/min

Property	Treated water	PG25
Heat transfer	Best	Somewhat lower specific heat and higher viscosity; needs more flow or a larger ΔT
Freeze protection	None	Protection for shipping, storage and cold environments
Biological growth	Requires biocide treatment	Biostatic at the specified concentration
Corrosion	Requires an inhibitor programme	Supplied with an inhibitor package
Typical use	Facility water systems; some TCS loops	The common default for TCS loops in OCP guidance

Type	Typical capacity	Location	Strengths and trade-offs
In-rack CDU	Tens to about 100+ kW	Inside the rack	Simple deployment rack by rack; consumes rack space; many small units to maintain
In-row CDU	Hundreds of kW to over 1 MW	In the row with the racks	Serves a row through manifolds; balances capacity and redundancy
Facility or centralised CDU	Several MW	Mechanical gallery outside the white space	Fewer, larger units; keeps maintenance outside the data hall; longer TCS piping
Liquid-to-air CDU (sidecar)	Tens to low hundreds of kW	Next to the rack	Rejects heat to room air; used where no facility water is available; limited capacity

Resilience: designing CDUs to the facility Tier objective

Liquid cooling makes heat removal more critical, not less. Cold plates hold only seconds of thermal buffer. If TCS flow stops, processors throttle or shut down very quickly. Resilience design must therefore cover:

Pump redundancy: N+1 pumps at minimum, with automatic changeover.
CDU redundancy: N+1 CDUs on a common TCS header, or 2N CDUs serving A and B manifolds for fault-tolerant designs.
Power to CDUs: dual-corded CDUs fed from A and B sources, with pumps and controls on UPS power so coolant keeps flowing through a utility failure and generator start. This is the liquid-cooling equivalent of continuous cooling.
Facility water continuity: chilled water or condenser water must also continue, through thermal storage, UPS-backed pumps or a high enough FWS temperature that the TCS can coast on stored thermal mass for the transfer period.
Concurrent maintainability: isolation valves so any CDU, pump, filter or manifold section can be serviced without stopping the others.
Leak management: leak detection, drip trays, automatic isolation valves and procedures for fluid spills.

Electrical engineering considerations

CDUs and liquid-cooling plants are electrical loads with their own design requirements:

Pump motors and VFDs. Large CDUs use variable-frequency drives on their pump motors. These introduce harmonic current that must be included in the facility's harmonic study and IEEE 519 evaluation.
Critical mechanical load on UPS. Putting CDU pumps on UPS increases UPS and battery sizing. The mechanical UPS load must be included in redundancy and ride-through calculations.
Feeder and protection design. Dual feeds, automatic transfer, selective coordination and arc-flash labelling apply to CDU power distribution just as they do to IT power.
Generator transient response. CDU pumps restarting together after a transfer create motor inrush on the generators. Staged restarts and soft acceleration reduce the step load.
Load dynamics. AI training loads can swing rapidly between high and low power. Cooling controls must track those swings without temperature overshoot, and electrical systems must handle both the IT and the cooling load changes.

Commissioning a liquid-cooled data hall

Flush and clean the TCS piping and manifolds to the specified cleanliness, using high-purity flush water.
Fill and vent with the specified coolant, verifying glycol concentration and chemistry.
Pressure test for leaks at design and test pressures, including quick-disconnect fittings.
Verify sensors and controls: flow meters, temperature sensors, pressure transmitters, leak detection and BMS points.
Load test with heat load banks connected through the cold-plate interfaces or rack manifolds, across the operating range.
Prove the heat balance on both loops at several load steps, and the approach temperature against the design.
Test failure scenarios: pump failure, CDU failure, power transfer to generator, valve failure and loss of facility water, confirming temperatures stay within the IT vendor's limits.

How Keentel Engineering helps

Keentel Engineering supports data center owners, developers and EPCs with the electrical engineering that liquid-cooled facilities depend on, and coordinates with the mechanical engineer of record and cooling vendors on the integrated design.

Element	Tier I	Tier II	Tier III	Tier IV
Utility service	Single	Single	Single or dual (not counted towards the Tier)	Single or dual (not counted towards the Tier)
Engine generators	N	N+1	N+1, continuous-rated, concurrently maintainable paralleling	N+1 or 2N, fault-tolerant paralleling and controls
Medium-voltage and low-voltage switchgear	Single bus	Single bus	Main-tie-main or dual buses; isolation on both sides of every component	Physically separated A and B switchgear
UPS	N	N+1	N+1 with dual output paths, or 2N	2N, 2N+1 or distributed redundant, compartmentalised
Distribution to IT	Single path	Single path	A and B paths; rack ATS for single-corded loads	A and B paths, physically separated
Fuel	12 h minimum	12 h minimum, redundant pumps	12 h minimum, concurrently maintainable supply	12 h minimum, fault-tolerant supply
Cooling	N	N+1	N+1 with maintainable piping and valves	Fault tolerant, compartmentalised, continuous cooling

The following are illustrative scenarios based on conditions typical of liquid-cooled data centers. They show how Keentel Engineering approaches the power and resilience side of liquid cooling; site details are generalised and figures are rounded.

Case Study 1 — Retrofitting an air-cooled hall for AI racks

Situation. An enterprise data center with a chilled-water plant and an air-cooled hall plans to install a row of AI racks at about 120 kW each, served by in-row CDUs.

Analysis. The study confirms that the existing chilled-water plant has thermal capacity, but at its 7–10 °C supply temperature the facility water is well below the hall's dew point, creating condensation risk at the CDUs. The electrical review finds that the existing mechanical distribution boards are single-fed and not on UPS, so a utility failure would stop CDU pumps for the 30–60 seconds before generators carry the load.

Engineered solution. A dedicated warmer-water secondary loop from the chilled-water plant through a mixing station, raising facility water to the CDUs above the dew point, coordinated with the mechanical engineer. On the electrical side, new dual-fed CDU distribution from A and B sources, with CDU pumps and controls on a mechanical UPS sized for the transfer period, and staged pump restarts on generator.

Outcome. The AI row operates without condensation risk, and cooling flow continues uninterrupted through a simulated utility failure during integrated testing.

Case Study 2 — Heat balance reveals a commissioning fault

Situation. During commissioning of a liquid-cooled hall, CDU trend data shows the TCS removing far more heat than the facility water appears to carry, with the facility control valve near fully open and a large approach temperature.

Analysis. A heat balance at several load steps shows the facility side consistently reporting about one-third of the TCS heat. Investigation finds a facility-side flow meter configured with the wrong pipe size and a partially closed balancing valve that had not been reset after flushing.

Engineered solution. Correct the flow meter configuration, reset the balancing valve, and re-run the load steps. Add heat-balance checks to the commissioning scripts and to the BMS as a continuous diagnostic alarm.

Outcome. Heat balances close within a few percent, the approach falls to its design value, and the valve operates in its controllable range, leaving cooling capacity for future rack additions.

Case Study 3 — Power design for a 40 MW liquid-cooled AI campus building

Situation. A developer designs a 40 MW IT building for AI training with direct-to-chip cooling, served by a warm-water facility system with dry coolers and trim chillers. The owner wants fault-tolerant cooling and minimal UPS cost.

Analysis. Keentel models the electrical load of CDUs, facility pumps and heat rejection plant, along with the IT load and its rapid swings during training. The analysis compares putting all mechanical load on UPS against putting only CDU and TCS pumps on UPS while relying on thermal inertia of the facility loop during generator start.

Engineered solution. CDU pumps and controls on 2N UPS with the IT load, facility pumps on a separate mechanical UPS sized for the generator transfer, and dry-cooler fans on generator-backed distribution. Harmonic studies include all VFD-driven pumps and fans, and generator sizing includes staged restart of the mechanical plant.

Outcome. The design maintains coolant flow through power events, meets the owner's fault-tolerance objective for cooling, and avoids oversizing UPS for loads that can tolerate a short interruption.

1. What is a coolant distribution unit?

A CDU is a liquid-cooling device that transfers heat from the IT cooling loop (TCS) to the facility water system (FWS) through a heat exchanger. It also pumps, filters and controls the coolant delivered to the racks, keeping the two fluids separate.

2. What are FWS and TCS?

The facility water system (FWS) is the primary loop from the cooling plant to the CDU. The technology cooling system (TCS) is the secondary loop from the CDU to the IT equipment's cold plates or other liquid-cooled components.

3. Why do the primary and secondary fluids need to be separated?

The TCS needs very clean, chemically controlled coolant at a stable temperature and pressure, because cold plates have fine channels and server components are sensitive. Facility water systems are larger and harder to keep that clean. Separation also limits how much fluid could leak inside the IT space.

4. What is approach temperature?

It is the difference between TCS supply temperature and FWS supply temperature. A smaller approach means a more effective heat exchanger and allows warmer facility water. OCP's CDU test methodology rates capacity at an approach of 5 °C.

5. What facility water temperatures are used for liquid cooling?

ASHRAE classifies facility water from W17 (up to 17 °C) through W27, W32, W40 and W45 to W+ (above 45 °C). Many liquid-cooled designs aim for W27 to W40, which allows extensive free cooling with dry coolers or cooling towers.

6. How is the heat removed by a CDU calculated?

Q = flow × density × specific heat × temperature difference. For PG25, 87 L/min with a 12.4 K rise carries about 72 kW. The same heat, plus pump heat, must appear on the facility side.

7. Why should the heat balance across the CDU be checked?

Because it must close in steady state. A heat balance that does not close usually points to a faulty flow meter, a misplaced temperature sensor, a bypass, air in the loop or an unsteady operating condition. It is a simple and powerful commissioning and troubleshooting check.

8. What flow rate is typical for direct-to-chip cooling?

A common basis is about 1.5 L/min per kW of IT load, which gives a temperature rise of about 10 K with PG25. Actual flows are set by the server vendor's cold-plate requirements and allowable supply and return temperatures.

9. Why is PG25 commonly used in the TCS?

PG25 provides freeze protection, is biostatic at its specified concentration, and comes with corrosion inhibitors for mixed-metal loops. OCP guidance specifies 24.5–27.5% propylene glycol by volume. The trade-off is slightly lower heat transfer than water.

10. What filtration does a TCS need?

Cold plates have fine channels that debris can block. OCP references a secondary filter of 50 µm or finer in CDU testing, and recommends fluid filtered at 50 µm or finer, preferably 25 µm, with continuous sidestream filtration in operation.

11. What does the CDU's control valve do?

It modulates facility water flow through the heat exchanger to hold the TCS supply temperature at its setpoint. At high load it opens; at low load it throttles. A valve operating near fully open at moderate load suggests insufficient facility flow, a fouled exchanger or an incorrect setpoint.

12. What controls the CDU pumps?

Variable-speed pumps are usually controlled on differential pressure across the TCS supply and return headers, or on flow. This maintains the pressure that rack manifolds and cold plates need as racks are added or their valves modulate.

13. What redundancy should a CDU have?

At least N+1 pumps within each CDU, and N+1 or 2N CDUs serving a common or dual header, depending on the facility's resilience objective. Power to CDUs should come from A and B sources, with automatic changeover.

14. Why should CDU pumps be on UPS?

Cold plates hold very little thermal buffer. If coolant flow stops during the seconds to a minute before generators pick up the load, processors can throttle or shut down. Keeping CDU pumps and controls on UPS maintains flow, the liquid-cooling equivalent of continuous cooling.

15. Does the facility water also need to continue during a power transfer?

It depends on the design. If the TCS can rely on the stored thermal mass of the facility loop for the transfer period, facility pumps may tolerate a short interruption. Otherwise, facility pumps, thermal storage or both need uninterrupted power.

16. What causes condensation risk in liquid cooling?

Any surface colder than the room's dew point. Facility water from conventional chillers at 7–10 °C can be below the data hall dew point. Warm-water designs largely avoid this, but cold facility piping must be insulated with a vapour barrier.

17. What are the main CDU types?

In-rack CDUs serve a single rack; in-row CDUs serve a row through manifolds; facility CDUs serve many rows from outside the white space; and liquid-to-air CDUs reject heat to room air where facility water is not available.

18. How is a CDU sized?

From the IT heat load, required TCS supply temperature, available FWS temperature, approach, allowable flows and pressure drops, and redundancy. Margin should cover future rack additions, fouling and the pump heat added to the loop.

19. How much power do CDU pumps use?

Pump power is flow × differential pressure ÷ efficiency. A 1 MW CDU moving 1,500 L/min at 2.5 bar with 60% efficiency draws about 10 kW, about 1% of the IT load. That heat is added to the TCS and must also be rejected.

20. Do CDU pump drives affect power quality?

Yes. Variable-frequency drives on pump motors draw harmonic current. Large liquid-cooled facilities have many such drives, so they must be included in harmonic studies and IEEE 519 compliance at the point of common coupling.

21. How do AI workloads affect CDU control?

AI training can swing power rapidly across a whole hall. Coolant temperature control must respond without overshoot, and pumps and valves must track the load. Simultaneous swings also affect the electrical system, so cooling and power controls should be studied together.

22. How is leak risk managed?

With leak detection at manifolds and rack connections, drip trays, dripless quick-disconnects, automatic isolation valves, pressure monitoring that detects slow losses, and procedures for response and cleanup. Negative-pressure TCS designs are another option in some systems.

23. What water quality does the TCS require at fill?

OCP guidance calls for thorough flushing with high-purity water (pH 5–8, low chloride, sulfate and hardness, and conductivity below 25 µS/cm), then filling with coolant soon after the final flush, preferably within 24 hours, to prevent biological growth.

24. How is a liquid-cooled hall commissioned?

By flushing and filling, pressure testing, verifying all sensors and controls, load testing with heat load banks, proving heat balances and approach temperatures at several load steps, and testing failure scenarios such as pump, CDU and power failures.

25. Can liquid cooling improve energy efficiency?

Yes. Liquid carries heat far more effectively than air, reducing fan energy. Warmer facility water allows more free cooling and fewer chiller hours, and in some cases enables heat reuse. The overall benefit depends on the plant design and climate.

Links were current at publication (October 2026).

Emergence and Expansion of Liquid Cooling in Mainstream Data Centers. ASHRAE TC 9.9 white paper.
Liquid to Liquid CDU Test Methodology and Performance Rating. Open Compute Project.
Guidelines for Using Propylene Glycol-Based Heat Transfer Fluids in Single-Phase Cold Plate-Based Liquid-Cooled Racks. Open Compute Project.
ASHRAE, Thermal Guidelines for Data Processing Environments. ASHRAE TC 9.9.
IEEE Std 519, IEEE Standard for Harmonic Control in Electric Power Systems. IEEE.

This article is general technical information for educational purposes. It is not engineering advice for any specific project and does not create a professional relationship. Temperatures, flows, pressures, fluid properties and capacities are indicative; actual designs must follow the IT equipment vendor's requirements, the cooling equipment manufacturer's data, the mechanical engineer of record's design and applicable codes. Verify the current edition of any standard or guideline before relying on it.

Case studies are illustrative scenarios based on typical project conditions, not records of specific client projects. Figures are rounded and indicative.

ASHRAE, OCP, IEEE and other names are the property of their respective owners. Keentel Engineering is not affiliated with or endorsed by these organisations or any equipment manufacturer.

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In 1995, Sonny Patel earned his Electrical Engineering degree from the University of Illinois. But degrees don't build legacies — action does.

For three decades, he has worked the power industry from every side of the table: 16 years as a utility engineer at Exelon/Commonwealth Edison; generation leadership across hydroelectric, industrial steam turbine, and a 9 GW renewable fleet; NERC Regional Entity Senior Compliance Engineer and Audit Team Lead, auditing some of the nation's largest utilities; and testing and commissioning lead on equipment up to 765 kV — the very top of the North American grid.Utility. Generator. Regulator. Consultant. Few engineers have seen all four seats. Fewer still have sat in them.

His experience spans nuclear, hydro, conventional generation, renewables, oil and gas, mining — and today's data centers, where he is authoring a three-book series on data center design. He is a Licensed Professional Engineer in six states and a Licensed Electrical Contractor in Florida (Unlimited EC) — he doesn't just design the work; he's qualified to stand behind its execution.Today, as Founder and CEO of Keentel Engineering, Sonny leads a nationwide team of engineers delivering substation design, power system studies, NERC compliance, and commissioning — done right, coast to coast.Three decades. Every side of the table. One standard: accountable engineering.

In 1995, Sonny Patel earned his Electrical Engineering degree from the University of Illinois. But degrees don't build legacies — action does.

Utility. Generator. Regulator. Consultant. Few engineers have seen all four seats. Fewer still have sat in them.

Today, as Founder and CEO of Keentel Engineering, Sonny leads a nationwide team of engineers delivering substation design, power system studies, NERC compliance, and commissioning — done right, coast to coast.Three decades. Every side of the table. One standard: accountable engineering.