An Integrated Guard Beats a Bolt-On, and Not Only on Looks

What the OEM needed

Initially an OEM had found a cross-flow fan suiting their equipment: 310mm impeller, 50 by 50 mm housing, 500 units. However, they needed an integrated fan guard on it.

That was the one change. Specifically, safety compliance in their market requires the impeller to be guarded, and they wanted it done at the factory.

The constraints

• First, a 24 VDC bus, so a DC fan was required.
• Next, 0-10V speed control for system integration.
• Meanwhile 85 m3/h against 15 Pa of system impedance.
• Noise capped at 33 dB(A), since the equipment sits in occupied space.
• Finally, -25C to +60C ambient.

Notably the base fan already met the airflow, pressure, power and noise figures. So this was never an aerodynamic problem.

Why an integrated fan guard won

We logged it as minor development: a mechanical adaptation rather than a redesign. Meanwhile the interesting part is the option we turned down.

The bolt-on guard, and why it lost

A standard third-party wireform guard is the obvious answer. Certainly it exists today, costs little, and passes the safety requirement.

Even so, we rejected it for three reasons, none of them cosmetic.

• First, it changes the external dimensions, so chassis integration becomes a moving target.
• Next, it needs separate mounting hardware, which adds parts to the bill of materials and steps to the assembly line.
• Finally, every added fixing is a new interface, and interfaces are where vibration starts.

In practice that third point matters most at 33 dB(A). A fan held to a limit that tight cannot afford a bolted accessory rattling against it.

What integration gives instead

By contrast an integrated fan guard is part of the fan as delivered. Consequently the published overall dimensions already include it, and the customer designs against one number rather than two.

So there is no separate part to source, stock, fit or leave off in service. Furthermore no bolted joint can loosen over thermal cycles.

What it cost

A distinct part number and a short development cycle. An integrated fan guard is not something you buy off a shelf this afternoon.

On 500 units that is easily repaid. For someone needing five fans guarded, a bolt-on wire guard is genuinely the sensible choice, and it is worth saying so.

Technical Specifications

The overall dimensions below include the guard. That is the point of integrating it.

Parameter	Value
Model Number	LWCD-30310MG-06-34
Airflow	85 m³/h / 50 CFM
Static Pressure	15 Pa
Voltage	24 VDC
Current	0.07 A
Input Power	1.68 W
Speed	2400 RPM
Speed Control	0-10V
Noise Level	33 dB(A)
Dimensions (Overall L x W x H)	364 x 50 x 50 mm
Impeller Diameter	Ø 30 mm
Impeller Length	310 mm
Operating Temperature	-25°C to +60°C
Bearings	Ball Bearing
Insulation Class	Class B
Certifications	CE, RoHS, UL Component Recognized

Technical Documentation

Final Product Specification Sheet: LWCD-30310MG-06-34

Here the PDF contains the final performance curves, electrical data, and material specifications, essential for the customer’s quality assurance and procurement teams.

The final assembly drawing details all critical dimensions, materials, wiring, and mounting points, required by the client’s mechanical engineers for system integration.

Here the image shows the production model of the LWCD-30310MG-06-34, verifying the clean integration of the custom-stamped aluminum safety grille.

If you have to add a guard

Adding a guard late is common. Whether it is an integrated fan guard or a bolt-on matters more than most people expect.

• Ask for the dimensions with the guard fitted. An integrated fan guard is inside the published envelope. A bolt-on is not, and discovering that after the chassis is drawn is an avoidable problem.
• Count the assembly steps, not just the part price. A separate guard means fixings, a fitting operation and a part that can be omitted. At volume those cost more than the guard does.
• Watch the noise budget. Bolted accessories introduce joints, and joints buzz. Where the acoustic limit is tight, integration is a performance decision rather than an aesthetic one.
• Confirm the guard is on the right face. Intake and discharge present different hazards and different airflow penalties. Guarding the wrong side costs performance without removing the risk.

See our cross flow fan range, the fan accessories section, or DC cross flow fans. Appliance safety follows IEC 60335-1.

Questions about guards

When is a bolt-on wire guard the better choice?

At low volume, on a prototype, or where the enclosure has room to absorb the extra dimensions. It is available immediately and costs little. The argument for integration is about volume production, tight envelopes and tight noise limits, and where none of those apply the simple option is right.

Does an integrated guard cost airflow?

Any guard does, and an integrated one is designed against the fan rather than fitted to it afterwards. The published figures include the guard, so what you read is what you get. With a bolt-on, the fan curve you were given was measured without it.

Why does a bolted joint matter at 33 dB(A)?

Because at that level the fan itself is barely audible, so anything else becomes the loudest thing present. A fixing that loosens slightly over thermal cycles produces a buzz that will dominate the measurement, and it appears months after the product ships.

Can the guard be added to an existing installed fan?

Mechanically often yes, though the airflow changes and the published performance no longer applies. If the duty point matters, either take the guarded variant or retest the assembly as built. Retrofitting a guard without rechecking airflow turns a compliant product into an underperforming one.