DC cooling fans for electronics and equipment enclosures · Frame size, airflow against static pressure, operating point on the system curve, fan laws, bearing type, voltage and control
A cooling fan for electronics moves air through an enclosure, power supply or server so components stay within their temperature limits; small DC axial fans are sized by frame (for example 40, 60, 80 or 92 mm square) and rated by airflow, static pressure, speed and noise. Ask three things first: what airflow the enclosure needs at its actual resistance (static pressure), which frame, voltage and control (speed signal, PWM) fit the design, and which bearing type suits the life and orientation required.
DC and EC axial cooling fans and small blowers for electronics, power supplies, servers, storage enclosures and equipment cabinets. Industrial centrifugal fans and ventilation fans, CPU heatsink-fan assemblies sold as thermal modules and domestic fans are outside this page except where compared.
01
The US Department of Energy sourcebook Improving Fan System Performance states that "In general, fan curves arc downward from the zero flow condition" (as back-pressure falls, airflow rises), that a fan operates where its performance curve intersects the system curve, and that adding resistance (for example closing an outlet damper) moves the operating point along the fan curve. It gives the fan laws: airflow changes in proportion to speed, pressure with the square of speed and power with the cube of speed, and notes that operating far from the best efficiency point raises bearing loads and noise. [1]
YCCFAN's DC fan table lists, for example, a 40 × 40 × 20 mm fan at up to 11,000 rpm giving 13.76 CFM and 13.89 mmH₂O, and a 50 × 50 × 20 mm fan at up to 7,500 rpm giving 22.78 CFM and 10.35 mmH₂O. [2] Because a fan's airflow falls as back-pressure rises, a fan cannot deliver its listed airflow and its listed pressure at the same time; ask for the full curve. [1]
Editorial calculation: 13.76 CFM is about 23.4 m³/h and 13.89 mmH₂O about 136 Pa. By the fan laws, running the fan at 80% speed gives about 80% airflow, 64% pressure and 51% power; check the cooled components at that reduced airflow before using speed control to cut noise. [2] [1]
Give the supplier the heat load and allowable temperature rise, the enclosure's airflow path and resistance (filters, grilles, cards), frame size and depth limits, supply voltage, speed control (fixed, PWM, thermal), tachometer or alarm signal, noise limit, operating temperature and humidity, orientation, life requirement and any ingress protection.
02
YCCFAN lists DC fans from 20 mm to 250 mm in 5 V, 12 V and 24 V versions with sleeve or ball bearings, including ultra-thin 20 × 20 × 6 mm fans for space-limited electronics, 25 mm fans with selectable bearing options, and 80–92 mm ball-bearing fans for server and industrial cooling, with control options such as selectable speed levels. [2]
Editorial note: ask the supplier for the full airflow–pressure curve, rated life and test temperature for the bearing offered, the starting voltage, and the wiring of speed-sensor (FG) or PWM control leads, and compare fans on the same test standard.
03
The suppliers reviewed list DC, EC and AC cooling fans and blowers; ask each for fan curves, noise, bearing life, voltage range, control and alarm options, protection rating and approvals.
04
SANYO DENKI's specification for its San Ace 140L 9LG fan (140 × 140 × 51 mm, mass approx. 790 g) lists two speed variants in the same frame. The 7,500 min⁻¹ version is rated at 62 W, 9.0 m³/min (318 CFM), 655 Pa (2.63 inH₂O) and 69 dB(A); the 5,000 min⁻¹ version at 22 W, 6.0 m³/min (212 CFM), 295 Pa (1.18 inH₂O) and 57 dB(A). The 12 V models have an operating voltage range of 10.2 to 13.8 V, the 24 V models 20.4 to 27.6 V and the 48 V models 40.8 to 55.2 V. [3]
Editorial calculation: the slower variant runs at 5,000 ÷ 7,500 = 0.67 of the speed and gives 6.0 ÷ 9.0 = 0.67 of the airflow, 295 ÷ 655 = 0.45 of the pressure and 22 ÷ 62 = 0.35 of the power, close to the fan-law ratios of 0.67, 0.44 and 0.30 [1], for a 12 dB(A) drop in sound pressure level. [3]
SANYO DENKI states the expected life as 180,000 hours, defined as "L10 life: 90% survival rate for continuous operation in free air at 60℃, rated voltage", and the fan has a PWM control function for external speed control. [3] Ask each supplier for life on the same basis (survival rate, ambient temperature, voltage and mounting) before comparing hours.
Life figures are only comparable when the failure definition matches. NMB Technologies' Fan Engineering handbook counts a fan as failed not only when it stops but also at a 15% drop in speed or a 15% rise in current, which it says gives a more conservative L10 and MTTF than counting hard failures only; it uses accelerated life tests at raised temperature plus ongoing reliability testing, in some cases for more than 10 years. It measures noise in an anechoic chamber with less than 16 dBA background per JIS C 9603, at 1 m from the inlet for DC fans and 1 m from the side for AC fans. [4] Editorial calculation: SANYO DENKI's 180,000 h L10 at 60 °C is about 20.5 years of continuous running; ask each supplier for the L10 temperature and whether parametric failures are counted, since a life stated at 40 °C with stop-only failures is not the same claim. [4] [3]
05
The last row sits outside the fan but belongs in the order: a guard or filter adds resistance, and added resistance moves the operating point along the fan curve. [1]
| Part | Role | Fix in the order |
|---|---|---|
| Frame and impeller | Move air. [2] | Size; depth. |
| Brushless DC motor and driver | Drive and control speed. [2] | Voltage; control. |
| Bearing (sleeve or ball) | Support rotor; set life. [2] | Type; life. |
| Lead wires and signals | Power, speed signal, PWM. [2] | Wiring; connector. |
| Guard or filter (system side) | Adds resistance. [1] | Pressure drop. |
06
YCCFAN's small DC fans and SANYO DENKI's 140 mm San Ace supply the published values; ask for airflow and pressure as a curve, since the listed maxima do not occur together. [2] [3] [1]
| Field | What it means and published values | Ask the supplier for |
|---|---|---|
| Airflow (CFM) | E.g. 13.76 CFM (40 mm), 22.78 CFM (50 mm). [2] | Curve. |
| Static pressure | E.g. 13.89 mmH₂O (40 mm) [2]; 655 Pa (2.63 inH₂O) at 7,500 min⁻¹ (San Ace 140L). [3] | Curve; max. |
| Speed (RPM) | E.g. up to 7,500–17,000 rpm by size. [2] | Speed; tolerance. |
| Noise Level (dBA) | E.g. 69 and 57 dB(A) for the 7,500 and 5,000 min⁻¹ San Ace 140L [3]; rises away from best efficiency; measured at 1 m in an anechoic chamber (JIS C 9603). [1] [4] | Value; method. |
| Input Voltage (V DC) | E.g. 5, 12, 24 V. [2] | Range; start voltage. |
| Power Consumption (W) | E.g. 62 W and 22 W rated input (San Ace 140L variants) [3]; scales with speed cubed. [1] | Value. |
| Operating Temperature (°C) | Bearing life basis. | Range. |
| Ingress Protection | Dust and moisture. | Rating. |
| Bearing Type | Sleeve or ball. [2] | Type. |
| Frame Size (mm) | E.g. 20–250 mm. [2] | Size; depth. |
| Weight (g) | E.g. approx. 790 g (San Ace 140L, 140 × 140 × 51 mm). [3] | Weight. |
| Lifespan (h) | E.g. 180,000 h L10 at 60 °C, rated voltage, free air (San Ace 140L). [3] | Hours at stated temperature. |
07
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Heat: [load W; allowable rise] Airflow: [needed at system resistance] Fit: [frame; depth; mounting] Electrical: [voltage; control; signal] Environment: [temperature; dust; moisture] Life: [hours; bearing] Noise: [limit; method]
4 companies list this product among what they make. Company figures are quoted from each company's own website; every card states where the relationship came from.
Lists DC cooling fans from 20 mm to 250 mm with DC blowers, AC and EC fans.
Product scope checked 2026-10-11
Lists DC, AC and EC fans with centrifugal and axial fans.
Product scope checked 2026-10-11
Lists AC and DC cooling fans and EC cooling fans with power components.
Product scope checked 2026-10-11
Lists cooling fans and small brushless DC fan motors with ventilation products.
Product scope checked 2026-10-11
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Rated maximum airflow is at zero pressure; in an enclosure the fan runs where its curve meets the system curve (DOE fan sourcebook). [1] [2]
By the fan laws, airflow follows speed, pressure speed squared and power speed cubed (US DOE). [1]
Sleeve or ball bearings; YCCFAN lists ball bearings on its larger industrial and server fans. [2]
SANYO DENKI defines its 180,000-hour expected life as the L10 life, a 90% survival rate for continuous operation in free air at 60 ℃ and rated voltage. [3]
Sources checked 2026-10-12. The US DOE sourcebook is a government guide to fan systems; YCCFAN and SANYO DENKI describe their own fans, and NMB Technologies' Fan Engineering handbook explains how one maker defines fan life and measures noise.
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