Detects Air Quality (Concentration of CO2, Alcohol, Benzene, NOx, Ammonia, etc.)
Working Voltage: 3.3 V
Output Type: Digital signal, Analog signal
Interface mode: ph2.0 - 4p
The DaguRobot MQ-135 Sensor Detecting Module detects air quality (concentration of CO2, alcohol, benzene, NOx, ammonia, etc.). It comes with two outputs digital signal and an analog signal. It runs on a 3.3 V working voltage and the interface mode is ph2.0 - 4p.
Note: MQ-135 can detect all the gases listed above, but cannot distinguish them. If you want to target one gas specifically, it is best to choose another sensor. The sensor also requires a heater to warm up the sensor. It is not recommended to use it with a smaller battery, as it will quickly run out of battery power.
If you are not satisfied with a product purchased from the Site, you may request a return within 30 days from the delivery date, unless the product is listed under the Return Exceptions below or is subject to specific return conditions noted on the product page.
This return policy also applies, as a minimum standard, to products sold and fulfilled by third-party vendors through the Marketplace.
Returns under this policy concern non-defective products. In the case of a confirmed manufacturing defect, remedies are handled under the Warranty terms, at the Vendor's discretion. See the Warranty section.
Return Conditions
To qualify for a refund under the 30-day return policy, all of the following conditions must be met:
A valid Return Authorization (RA) number must be obtained prior to returning the product. Returns without an RA number will be refused.
The RA number is valid for 30 days. The returned item must be received within that period.
The RA number must be included with the return.
Products must be returned in unused, unmodified condition (e.g., no scratches, alterations, missing parts, or signs of installation/use) and in their original packaging, suitable for resale.
Shipping fees are non-refundable. Return shipping costs are the responsibility of the customer, except in cases of a product confirmed defective through RobotShop's troubleshooting process or of a verified shipping error by RobotShop.
Refunds are processed within 7 days after receipt and inspection of the returned item.
A $100 cleaning fee may apply to domestic robots returned in used or unclean condition.
A 20% restocking fee may apply to large-quantity returns of items ordered specifically for the customer from the manufacturer or not part of RobotShop's standard inventory.
Return Exceptions
The following products are not eligible for return or refund under this policy:
Used, damaged, or modified products — Items that show signs of use, wear, or alteration, making them unsuitable for resale.
Consumables — Use and wear-and-tear components, altered or depleted through use (e.g., batteries, belts, brushes, gears, filament, tires, disposable bags, lubricants, greases, waxes, etc.). Not eligible for return once opened or used.
Perishables — Goods liable to deteriorate or expire rapidly. Not eligible for return.
Sealed goods (health or hygiene) — Items sealed for health-protection or hygiene reasons (e.g., masks, gloves, odor-absorbing products). Not eligible for return once unsealed.
Build-it-yourself products and items requiring customer assembly — Including robots & kits, robot parts, and other products requiring assembly or soldering. Not eligible for return once assembled, soldered, or installed.
Digital Goods, Software, and Apps — Final sale only, due to licensing restrictions.
Clearance Items — Products identified as clearance or final sale, including end-of-life or discontinued items.
Custom-made, personalized, or special-order items — Products manufactured, configured, adapted, or built to the customer's own specifications and requirements.
On-Demand Items — Standard catalogue products not stocked by RobotShop and ordered specifically to fulfill a customer request.
While the same return policy applies, these orders require a separate contact process for returns.
RobotShop Fulfilled Orders → submit a support ticket from your account under My Support Tickets.
Marketplace Vendor Orders → submit a ticket from your account under My Marketplace Tickets to contact the vendor directly.
Note: Marketplace vendor products are normally labelled with SKUs starting with RM, and identified on the product page with the mention "Sold and fulfilled by [Vendor Name]".
