If you have any other questions, please don’t hesitate to contact us. Most of the customers will buy the wrong items of the quick couplings without understanding of the thread type and size and bring lots of issues on return and refund. Before you buy the replacement for your current quick coupling, you can ask us any question to check it.

frequently asked questions

Question for Products

How to Find the correct Quick coupling

For personal buyers, they usually wanna find the replacement of the quick couplings on their devices. In order to find the correct Quick coupling to replace the current one on your hydraulic equipment or hydraulic tools, you need to check some thing carefully. There are some tips help you find the correct replacement quick coupling

Tip 1, The Item number of your current quick coupling. Usually, there would be item numbers printed on the quick coupling, it is very important to help you find the right items from other brands or direct from the manufacturer like us. That can save you pretty much money . you can find check this file to help. or just contact us for help.

Tip2,  ISO standard is another key track of finding the correct replacement quick coupling. If the item number on your current quick coupling was weared off, then you can take a photo to our customer support to help you find the correct item, we will check it from the shape to meet the ISO standard coupling. The flat face quick coupling usually comply with ISO16028, the universal quick coupling usually comply with ISO 7241 A or ISO 7241 B. ISO 5675 is special for agriculture equipments, and the ISO 14540 special for high pressure tools and some hydraulic columns and liftings. 

Tip 3, The thread is the most important thing, usually we will find 5-10% customers bought the wrong items, just because they don’t know the thread. For quick coupling there are some Thread type. NPT, BSP, BSPT, M thread etc. In North America, usually NPT this the most popular thread. In EU, usually BSP (BSPP) is popular, and on some water applications (Stainless ISO B quick coupling) they like BSPT or NPT..  you can read the articles on our website to know something more about the thread. Usually the thread size not equal to the dimension you can measure directly from the thread. The pipe thread size usually named the pipe inner hole size. That is why usually newbie easy to make a huge mistake on the tread size. most of our return and refunds reasons are from this, the misunderstanding of thread size.

With the item number matched, the right ISO standard part and the right thread choice, you can find a perfect replacement quick coupling for your equipments or tools. If any question, please contact us by the methods on the website. we will reply you as soon as possible. Livechat would be the most effective method. 

How to check the thread on the Quick couplings

The good way to check the thread is to check the item number on your quick couplings.It is because usually the quick coupling brands will mark all information with the item number. The second way is to measure the inner diameters of the thread, but DO REMEMBER, that the dimension you measured is not equal to the Thread size. You need to find the thread list to find the correct thread size. The usually named the thread standard. For example NPT 1/2″, you cannot get the dimension 1/2″ from the thread, you can see the article about the NPT

If you have any question about the thread, you need to inquire the customer support, to help you find the correct thread type and size. It is very important. 90% customers that bought the wrong items because of the wrong thread choosen.

How to Check the Pressure request for your Application

Most of the hydraulic applications are less than 5000 PSI, you can read the nameplate on your equipment, most of the quick couplings can work at the normal pressures. And the burst pressue of the quick coupling usually 3-4 times than the working pressure. So it would be safe to use most quick couplings on your equipments. The Stainless steel quick coupling would be less pressues. So if you check your equipments will work at the pressure over 6000 PSI, please don’t use a stainless steel quick coupling. If the high pressure applications, you need to check the quick coupling item carefully. usually high pressure at 76Mpa (10000 PSI), the structure or the size would have a limited. You will find the pipe size is less than 3/8″. 

If you would like to check the pressure of the quick coupling and your equipment. you can easily find on your equipment nameplate and find the matched quick coupling. JUST CHECK IT if it is a high pressure applicaiton.

Do the shape of the quick coupling important?

The quick couplings from different brands usually will have a very different shapes, they are not very important, because the features are same, and the data (flow rate, pressure rate and working pressure) usually same too. Because they are produced comply with the ISO standard. You need to check the shape and some dimensions, if when you setup the quick coupling, they will go through some holes. We have some experience that when they bought some quick couplings, they will go through the threading, then our quick coupling is “fatter”, they cannot be used on their equipments. We now have improved the shapes like Flat face quick coupilng 1/4″.

If there is not special requirements, the shape is not so important.

The surface finished important?

The surface finished usually the imporatant for the protection of the material and for the different fluid. The plating usually have 3-Cr, Zn-Ni alloy, epoxy resin etc. they usually plating for the material of carbon steel. And the stainless steel 304 or 316 and the brass material quick coupling usually don’t need any plating. but they have limited on fluid material choose.

Stainless steel 304 or Brass material quick couplings are usually used for the water applications, and 316 usually used for food industries. Carbon steel materials can used in many different applications.

The Sealing ring Material different?

Seal materials (o-ring) is very important for the poppet type and flat face quick couplings, the ball valve don’t need to the seal material. The seal materials will have different temperatue available and the different fluid. 

The common material is Nitrile rubber -(NBR, HNBR, HSN, Buna-N): a common material for o-rings because of its good mechanical properties, its resistance to lubricants and greases, and its relatively low cost. The physical and chemical resistance properties of NBR materials are determined by the acrylonitrile (ACN) content of the base polymer: low content ensures good flexibility at low temperatures, but offers limited resistance to oils and fuels. As the ACN content increases, the low temperature flexibility reduces and the resistance to oils and fuels improves. Physical and chemical resistance properties of NBR materials are also affected by the cure system of the polymer. Peroxide-cured materials have improved physical properties, chemical resistance and thermal properties, as compared to sulfur-donor-cured materials. Standard grades of NBR are typically resistant to mineral oil-based lubricants and greases, many grades of hydraulic fluids, aliphatic hydrocarbons, silicone oils and greases and water to about 80 °C. NBR is generally not resistant to aromatic and chlorinated hydrocarbons, fuels with a high aromatic content, polar solvents, glycol-based brake fluids and non-flammable hydraulic fluids (HFD). NBR also has low resistance to ozone, weathering and aging. HNBR has considerable improvement of the resistance to heat, ozone and aging, and gives it good mechanical properties. (wikipedia

upgrade material Fluoroelastomer – (FKM): noted for their very high resistance to heat and a wide variety of chemicals. Other key benefits include excellent resistance to aging and ozone, very low gas permeability and the fact that the materials are self-extinguishing. Standard FKM materials have excellent resistance to mineral oils and greases, aliphatic, aromatic and chlorinated hydrocarbons, fuels, non-flammable hydraulic fluids (HFD) and many organic solvents and chemicals. Generally not resistant to hot water, steam, polar solvents, glycol-based brake fluids and low molecular weight organic acids. In addition to the standard FKM materials, a number of specialty materials with different monomer compositions and fluorine content (65% to 71%) are available that offer improved chemical or temperature resistance and/or better low temperature performance.

Question for buying and return

Where to buy our products?

For personal buyer in US, our website and our Amazon store is the best way buying our products. All products we recommend shipped from the Amazon warehouse. Buy from our website, the website backend will ship on Amazon backend with Amazon Multi-Channel Fulfillment (MCF). Buy from Amazon.com, Amazon FBA service will ship the goods quickly.

For other countries, we recommend buy from our website, all products will be shipped from our factory directly. We will add shipping fee website backend, we usually use UPS or Fedex to carry the goods. 

When we will ship the items you buy?

US customers will get the goods within 5-10 days shipped from Amazon warehouse. 

Other countries the products will be shipped from our factory, usually it will take 5-12 days

Why you should ask questions if you are not fimilar with the products?

When you wanna buy quick couplings, there must some data you need to check, it will help you find the correct replacement for your application. If you don’t know the quick coupling, you need to ask us for help.

  1. Check your current quick coupling item number
  2. Check the thread type and size
  3. check the ISO standard
  4. The valve type
  5. the working pressure of your equipment
What the payment methods we accept?

Curretly we accept the payment of Credit Card, PayPal account, and TT to our company bank account.

Credit Care service from Stripe, most of the Credit Card can pay from this service.

Paypal can supply the best trade assurance order service, if you have any doubt, to choose Paypal it the best way.

TT to our company bank account is for the business customers.  We will hold the orders for 30 days, as soon as we receive the payment, the goods will be shipped.

How to ask for return and refund?

Damaged Goods; Goods Received in Error; can ask for return or refund. just contact us by livechat or contact form, we will send you return shipping label, and arrange the return and refund process.

If other reasons, you need to contact us.

What is the Restocking fee?

The costs of return shipments and a 15% restocking fee will be charged to you on all returned goods other than when: (i) the wrong goods are shipped to you by AKJia, (ii) goods are received in damaged condition, or (iii) the goods are subject to a warranty claim.

How to return a product?

With contact with our customer service, when we accept  your return, our customer service support will send you return label, and ship back by USPS.

Question for Account Funds

What are the account funds?

Account Funds is the funds you can use for buying products on our website directly. 

How to get the account funds?

The only way to get account funds is get your unit Referral coupon for your account. The referral coupon can have 5% off and another 5% referral fee for your account. 

How to ask pay the account funds to your Paypal account?

Just submit the request for pay form on the account page – account funds

Why we just use the Referral coupon?

Referral coupon can share profit to our customers, quick couplings usually replaced periodically, if you feel our product and service are good, you can introduce us to your friend, we are pleased to share profit to you.

How to be a referral member?
  • you have bought products from us through our website.
  • you wanna share our products to your friend or through your social medias or any other methods.
  • Email us by info@akjiainc.com list the order number, email address, and the request.
  • we will check and confirm to you by email.