Advice Required! Purchasing parts from Unknown Manufacturers and Distributors (Amazon for example)

Hi all

i am in need of some peristaltic pumps for a project (or 2!) and of course the first place i looked was Adafruit and picked up one of their small pumps ( but 100ml/minute is nice for some applications - however I now need some higher flow pumps - 500ml/minute would be good.

In Sweden I have found it hard to find anything really until recently when opened up - now there are a few options around (though prices start to climb rapidly!) - it seems the most common variant that suits my needs is a 12v “G928” ( which has many sellers - they all appear to come from the same factory.

im normally happy to pay a premium to someone like Adafruit (as a hobbyist) and have them take the risk of screening suppliers, ensuring compliance to RoHS etc - so my question is if someone has any advice on how to screen companies like this and it might be amazon, alibaba, ebay… whatever; places where its easy to sell things of potentially questionable origin and quality.

(for some parts I am less concerned than others, however one project for these pumps is a food project with my kids, so im much more concerned about quality)

i might be being overly cautious, but in the off chance im not… :slight_smile:

You seem to have a good feel for the idea that buying through a reputable distributor like Adafruit is paying for ad-hoc quality control. They very likely are buying from a range of different factories and then certifying that the item in question (pump) hits their specified needs. They might have looser needs than you do.

When I move outside that realm for my own product needs, I do two things:

  • Start slow
  • Build relationships

By start slow, I mean I will sample a few products at a time, instead of buying the entire amount for my project. So if I need 100 pumps for an upcoming design, I will only buy 1 or 2 but from a wide range of suppliers. Then it’s important to set up criteria for incoming testing. The nice thing about having that rigor is you can do easier comparisons (if not time consuming), and also use that same test criteria to test future pumps, should you need to find a new supplier. This is what large engineering and manfuacturing companies do as well.

For building relationships, it’s important to start from the beginning. One example I have is I was trying to source an odd cable from a range of suppliers on Alibaba. I worked within the Alibaba communication system and had to keep up with the 3 or 4 that I engaged at the beginning of the process and keep communicating my needs as we moved towards production. They will be eager to win your business and sometimes a bit…persistent. At the beginning, I am always careful to mention that I will be happy to pay for samples and shipping. I am very careful to also be honest with quantities. I am surprised that many factories in China will still service low quantity needs, as many of them are set up for that (locally they service small orders) and they also want to offer other services and win future business. So from that perspective, it’s a symbiotic relationship. I have found the agents on the other end of the chat to be very pleasant. On the Amazon side of things, it’s much less relationship based, so if you think you will have custom needs, I would maybe go more towards a marketplace solution like Alibaba.

Please let us know about your experience as you try these things out!

cheers @ChrisGammell - within the industrial realm where the potential for future sales is there, i can agree that the approach of building relationships etc is the way to go. in the past I have been fortunate to have sourcing departments to assist (a good sourcing department can be worth their weight in gold!) however my experience (on the hobby side) has been that i often struggle to get through the door with a message (as an example, I am trying to source food grade silicon tubing for this project and, at least in Europe, it’s almost impossible. I spoke with McMaster Carr, but they won’t allow their stock to be distributed outside of the US - but this will be another post perhaps! but point being - the local distributors here only want to deal in B2B accounts and your mails, calls etc go unanswered)

I can imagine my quality control is higher than perhaps many retailers, for sure! and a cursory glance of the web will turn up the Adafruit pumps all over the place. And whilst they may fail or not perform to spec, that is one thing - from an import/export perspective, large retailers like Adafruit, Digikey, Mouser etc to have reputations to protect, and so I feel you (should?) be able to rely on them to at least ensure the parts are RoHS compliant, aren’t going to contain dangerous materials, and that they don’t present safety risks either (knock off USB chargers i’m looking at you!)

A few years back there was an incident where toy keyring spy-cameras that were being imported from china in bulk had massive quantities of lead in the plastic…

I bought some from Runze directly and am quite impressed with the quality. I think the model I bought will fulfill your specs. I had the idea to use 2 of them at the same time feeding a mixer nozzle with YZ1515X.

For those playing along at home and interested in learning from my experience - some relevant links

According to the seller is responsible for ensuring compliance and safety: this link provides a nice list of relevant standards (a good reference list in general!)*

Thus, Amazon themselves take no steps to ensure compliance. I have contacted the seller and asking for their compliance - CE, RoHS, FMC etc - I will likely try and contact multiple sellers.

i can suggest, that for someone like Amazon, it would be good to require those notes as part of the listing

  • please note, this is for Sweden, and your mileage may vary!

When it comes to parts from less-than-reputable sources, I’ve taken a risk-based approach. If the risk and results of something failing/breaking/being-wrong is low, then go for it. If it is high, then you should figure something else out.

For example, for my personal hobby projects, I regularly buy from those types of sources. If my cute widget at home breaks, the worst thing that happens is that I’m annoyed. And I can find a replacement in my spare time, whenever that may be. Also, I make my designs very tolerant to things being wrong.

  • “The part says it uses M4 bolts, but when it shows up, they’re #4-40? Fine!”
  • “The battery says 6Ah, and doesn’t spec the ESR? Turns out the ESR is so high, that you can’t use the battery for much more than anything over 0.1C!”

If it’s a project where I’m being paid for it, such as a full-time employment or consulting situation, I will almost always pick from more reputable sources, even if 5x the cost. The amount of money (in dollars spent and my time) it costs me later is always much more than the initial savings. This waste can come from things like:

  • The parts not being made anymore.
  • The datasheet being wrong or missing information.
  • The part changing without notice.

If that project you are working on is for a company, maybe have one of them reach out to the vendor you want to speak to. They can make the introduction, and you can continue the conversation. If need be, the sponsoring company could also make the purchase as well (assuming they’re already going to be billed for it through you).

cheers @seth.kazarians - agree and when it comes to functionality concerns, that’s realistically the best approach - and I am more than ok with accepting that what I receive may look different… the pinout might not be correct and all those things, that with design I can fix, or source another part.

the question I raise here is about ensuring the safety & regulatory side of things - and more so for a home hobbyist who likely doesn’t have access to sophisticated test equipment. These are things we can’t design around. I don’t want to buy a component that has an inherent safety risk and use it in a project - I especially don’t want to give that to my kids or someone else to use. This is why I tend to prefer suppliers who must take the legal risk of import and compliance and have a brand/reputation to protect - for me it’s worth the extra money and that is part of my risk assessment.

Companies like Adafruit, Sparkfun, digikey, or my local retailers in sweden, besides the reputation, are legal entities that are easily located and the authorities can take action against in case of breaches. I admit this is a long shot - but that fact means that, at the very least, they should vet parts for compliance - looking at (peristaltic pump) you will see
so i feel confident that the pump is going to be ok to handle - with some food safe tubing (again, as noted by Adafruit in the product description) then the pump is ok for food projects

now, on places like Amazon, or eBay there is not really that safety net anymore - eBay/Amazon etc put the burden on the seller, who could be anyone or anywhere… and given the margins involved, there is less incentive to do the due-diligence.

as noted above, I reached out to the sellers asking for compliance documentation, and got a reply today that no answer was given!

summarily (!) my concerns are much less on function than safety - the last thing i want is to pick up a pump like this, give it to my kids for their garden project and find it’s been leaching lead or something into the soil… the race to the bottom can be treacherous!

Regarding CE marking, if you are importing goods you are responsible for checking it has the needed documentation wrt safety etc

I do not know how it works when one orders goods from other countries bypassing importers

@kvk this is, at least to me, what is perhaps so confusing with places like Amazon or eBay. Since they (amazon/ebay…) put the responsibility on the seller - but the seller invariably is not in the EU (or US) so, in that case who is the importer?

  • as I am the one who is bringing the parts in from a seller/manufacturer in China, and if there were duties to be paid, they would likely be levied to m - so does that make me the importer and therefore responsible? (if i was to buy a bulk lot on alibaba and resell i would imagine I would be responsible - so is this the same case when I buy from a manufacturer in China on Amazon?)
  • because the seller is selling them in the EU via an EU based site ( for example) are they responsible?
  • does Amazon have any responsibility - at all (as the owner and operator of the sales site)?
  • does Amazon have any responsibility when the seller uses “FBA” (Freight by Amazon - meaning they are doing the logistics?)

this is what i find on Amazon - and as you can see it’s purely on the seller

when you look at the ad’s, there is no mention of CE; RoHS or anything else at all… (it’s also often very bad translations, so it’s hard to even trust the wording!)…

If you are selling items in the EU you are per definition an importer, so you will be responsible for checking that the seller has fulfilled all rules

In the old days you could put that responsibility on the seller abroad

I guess Digikey is just a reseller but if you ask them for CE documents they need to be able to provide them

I’m not sure that’s true in all cases. This thread has been considering the online market places like eBay, Amazon, Aliexpress. Recently they have been forced to start taking VAT on top of the listed price for all items sourced overseas where VAT hasn’t already been included in the price. They then have to send it straight to UK treasury. The Chinese supplier touches nothing - it’s like a “taxman in the middle attack” to butcher a phrase (I don’t consider paying tax an attack, in this sense - just implying that it’s out of control of sender or receiver). So if the online market places are now responsible for the VAT, it certainly suggests that UK government sees the marketplace as the importer, regardless of whether you resell.

@kvk & @smerrett79 - thanks for the replies - it seems that this is a confusing topic for others, not just myself. The rules, regulations, responsibilities are all very unclear and it’s easy to make assumptions.

I have reached out to amazon now to clarify - in essence, as per their policies

  • who is the importer, and does it make a difference if its “Freight by Amazon”
  • who is responsible for handling compliance and documentation (both that its available and correct)
  • why is basics like CE marking etc, not part of the listings

again, i am sure i am overthinking this - but in the race to the bottom it can be so easy and tempting to take shortcuts and I feel in a system like this, which is driving the race to the bottom, its easy for things to fall between the chairs and each side will point a finger at the other - meaning it’s you and me that end up copping the mess

This is an area that I believe continues to have changes, but here’s my opinion based on my experience with Amazon as a buyer and as a 3rd party seller.

When you buy items on Amazon, you are buying the goods from the seller. The item belongs to the seller. The seller is using Amazon as a service to facilitate the transaction, but the item belongs to the seller while being stored in Amazon’s warehouses. The buyer is buying the product from the seller, not Amazon – and when you click “buy” on the website, you are actually placing an order with the seller through Amazon’s interface. While the payment goes to Amazon, you’re not paying Amazon. Amazon is simply collecting the funds on the seller’s behalf. Amazon performs marketing and fulfillment services and charge their fees to do so, but Amazon is not the seller UNLESS the listing specifically states that the product is being sold by Amazon).

Amazon acts as a fulfillment service for 3rd party sellers; it’s the physical-goods equivalent of web hosting – Amazon, for the most part, does not take ownership/responsibility of the goods. However, I have heard that recent rulings have made Amazon responsible when the original sellers cannot be reached. (

When you, as the seller, send stuff to Amazon, the importer is you, even when you use Amazon’s freight/shipping arrangements. You are paying them to facilitate the transaction, but you are the importer, while Amazon is the consignee.

From Amazon’s perspective, they did not participate in the selection/vetting of products being sold by 3rd parties, so they are not responsible for the products until and unless they hear complaints from customers. If there are enough issues with a product, Amazon will delist it from the marketplace. Amazon will also refund customers, sometimes at Amazon’s cost, when there are any customer satisfaction issues. However, they are doing that only to refund the purchase, and not because they take ownership of the problem.

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seems reasonable - i would then expect that the seller is able to provide compliance documentation on request. we’ll see what happens!

@ToyBuilder your reply basically agrees with the official answer I received from Amazon just now - the seller is the one who takes responsibility for the goods, compliance and documentation.

I have reached out to the seller, so lets see where that lands! its interesting to follow a thread, and im learning a lot in the process

Depends on the seller. Many sellers have no clue what they’re selling. They just find something that they can put into Amazon listing to make a buck. If you look at the seller details, their carried items will look like USB batteries, T-shirts, telecom gear, kitchen utensils, and camping equipment. (Or some such.)

They still pass this to their suppliers - who basically guarantee (or claim) to have met required approvals. Unlike Amazon/Ebay Digikey has people there checking that suppliers are mostly following the rules, although it’s far from ironclad in many cases.

As an example - an old (from 2016) post from Seeed shows they didn’t bother with EMC ( but it’s not clear they ever did, but it still shows up on Digikey (and Digikey EU). A lot of people do ‘it’s your own problem’ for small little boards like that.

Actually meeting all the CE requirements and chasing down all the certs would be a full-time job (and the reason companies have departments doing this…), almost every “not huge” company I’ve seen does a kinda best-effort work.

This is where the words “marketplace” comes in. There’s a difference in the role that a reseller provides versus a marketplace facilitator. Digi-Key opened up their “marketplace” to receive and direct orders to the 3rd party sellers, separate from items that they sell. If you have a mixed order that contain a marketplace item, they actually separate the order into two invoices to maintain that distinction.

I am still not sure how it really works

For example EU also talks about distributors and their obligation to check suppliers

It is compelling to earn money on reselling or distribution, without taking responsibility

I know several small companies that do not comply to all the rules. It’s simply too daunting for them and the small businesses could probably not exist if they did everything to the letter.

interestingly, i just got a recommendation from Udemy for this course:

Certifications & requirements when importing from China