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Guideline of Sample Test (Trigger Sprayers)

It’s an essential step to require sample test before proceeding bulk order. We carry out a free sample policy to encourage our customers to test samples. Especially for trigger sprayers, there are a wide variety of trigger sprayers with different design, material, mechanism and functionality. And trigger sprayers can be highly customized including tailored colors, dip tube length, spray pattern and chemical compatibility. A sample approval before bulk order will minimize the chance of unnecessary loss and complaint.

This article will introduce standard steps how to test pre-production samples (PPS) of trigger sprayers.

Sample testing procedures including

  • 1. Appearance Check: color match, weight check

  • 2. If the bottle neck fit perfectly, leak test.

  • 3. Dip tube length
  • 4. Function test: output, spray angle, air venting and fatigue test
  • 5. Chemical compatibility test

1. Appearance check

The first thing we should do when we open parcel sent from supplier is check samples’ appearance. Hold sample in hand and check if there is plastic flash, scratch, contamination, short shots, poor assemble etc. visual defects. If you required a color match sample, use color sample or Pantone color card. However, even you required a standard color sample. For example white color, it’s also necessary to check if the spray pump can fit on paired bottle. There are numerous variations in white color like pearl white and creamy white.

Weight check is an important but easily neglected testing step. There are countless factories making trigger sprayers, and their product pictures on website can look like the same thing. But different plastic wall thickness, invisible inside structure can lead to different dispensing performance and longevity. Weight check is one of useful methods to measure this. Simply put trigger sprayers(without dip tube and not used) on gram weigher and calculate average weight for at least 6 pieces of samples.

2. Neck finish compatibility

Make sure the trigger sprayers’ neck finish can pair with targeted containers, for example 28/400 trigger sprayers should pair with 28/400 neck finish bottles. Manufacturers should follow the same standard to make thread and closure which is established and issued by GPI (Glass Packaging Institute) and SPI (Society of the Plastics Industry). However, because of variables in manufacturing process and standard tolerance, even the same standard size trigger sprayer and bottles from different manufacturers may not perfectly fit. To be surefire, we need to move forward one more step. Firstly, require a technical drawing from supplier. Then use a ruler to measure samples’ dimension of at least “T” ,“E”, “H”. Compare the data with technical drawing and corresponding bottle’s dimension to make sure they fit.

bottle neck thread dimension

“T” Dimension

Outside diameter of the thread. The tolerance range of the “T” dimension will determine the mate between bottle and closure.

“E” Dimension

Outside diameter of the neck. The difference between the “E” and “T” dimensions divided by two determines the thread depth.

“I” Dimension

Inner diameter of bottle neck. Specifications require a minimum “I” to allow sufficient clearance for filling tubes. Linerless closures w/ plug or land seal & dispensing plugs/fitments require controlled “I” dimension for proper fit.

“S” Dimension

Measured from the top of the finish to the top edge of the first thread. The “S” dimension is the key factor that determines orientation of the closure to bottle and the amount of thread engagement between the bottle and cap.

If this measuring work seems overwhelmed to you, no worry. We can skip to leak test. Afterall the main concern about neck finish fit is to prevent contained fluid from leakage. The normal method about leak test: Fill the solvent no less than 3/4, close with trigger sprayer with defined force and turn nozzle in off position, place bottle upside down at least for 24 hours, then confirm the leakage state.

If a vacuum test machine is available, then fill the solvent no less than 3/4, close with trigger sprayer with defined force and turn nozzle in off position, lay the products inside the vacuum machine and reach the specified value of vacuum,then confirm the leakage state after 15mins.

(Vacuum test machine)

shipper trigger spray pump

(shipper trigger sprayer)

Note: Hangzhou Moonlight Cleaning Products Co,.Ltd are carrying shipper trigger spray pump features anti-leak even when nozzle in on “spray” pattern. This design can prevent chemical leakage when product falling over by accident during usage. If you got similar trigger sprayer samples, the leak test should be operated twice with nozzle on both “ON” & “ OFF” positions.

3. Dip tube length

Dip tube length of trigger sprayer samples should perfectly fit with paired bottles. Too long and it will bend too far in the bottle, too short and it won’t be able to reach product at the bottom. Standard measurement for dip tube length should be from bottom of gasket to the notch end of dip tube. Then measure the overall height of bottle, from top of bottle neck to the bottle bottom. It is also important to note if the container you are using features a “push up” at the bottom, meaning the bottom is raised. If there is a push up, subtract about 3/32” from the container length you previously measured to compensate. This step ensures proper flow through the dip tube.

Now, you get the numbers for dip tube length and bottle height. If the dip tube is flexible one, add about one inch to the bottle height, so that the dip tube should slightly bend toward the wall of your container, to maximize product dispensing.

If the dip tube is rigid, normally it’s fine to be equal to bottle height, but make sure end of dip tube is cut in angular or V-shaped no matter it comes with filter or not. Because flat dip tube end may sit flush to the bottom of bottle causing blockage and prevents pumping. Also, we have bend rigid tube available as well as some other suppliers, to prevent this happening.

(flexible dip tube)

(Rigid dip tube)

The best practice to ensure the dip tube fit is testing with fluid. Fill in small volume fluid in bottle and check if it can empty the bottle or not.

4. Function test

Function test should be the main section in whole sample test. The scores on function test determine to a great extent if the sampled trigger sprayer can bring good product performance and user experience.

Prime times:

full fill bottle with fluid, count how many times of squeezes is used until the first spraying come out. This test somehow reflects the airtightness in piston and cylinder.


operate at least 30 times squeezes, spraying the fluid into a wide opening measuring cup. Then measure the total volume of fluid, divide corresponding squeeze times to get output.

Spray angle:

While a certain spray angle is needed, operate this test. Place trigger sprayer’s nozzle end at a certain distance from target surface(normally in 20cm), then squeeze trigger and measure the diameter of the wet area on surface. This should be operated indoor and spray fromabove down to minimize impact from gas flow and gravity.

Leak test:

press trigger at least 30 times to check if leakage occurs on nozzle end and piston, test on both spray and stream patterns.

Foaming test:

if trigger spray pump comes with foam nozzle, foaming test should be operated and check how long the foam can cling on target surface.

Air venting:

normally air venting hole is visible under the gasket seal. Air venting hole prevent bottle from collapsible after multiple squeeze. So don’t forget to check if your test bottle is collapsed after multiple squeezes.

Fatigue test:

This could be the hardest part of test at customer’s end, as it may take thousands of squeeze and humans’ hand can’t bear for that. If not applicable on your end, ask supplier to proceed this test and submit test report. The purpose of this test is to ensure the trigger sprayers can empty chemical without defect, specially for those paired with high volume reservoirs. Supplier usually have customized machine to operate this test.

5. Chemical compatibility:

Most sprayer bodies are made of polypropylene (PP), but other components of the sprayer can be made of various plastics including high density polyethylene (HDPE), low density polyethylene (LDPE) or polyethylene terephthalate (PET). whereas some customers have needs to dispense strong acid / alkali or oily chemicals, a chemical compatibility test should be operated in those circumstances. Usually a soak test will be practical if applicable, disassemble the trigger sprayer samples( or ask supplier send separated components), take out all key components which may contact with chemicals during usage including nozzle cap, nozzle valve, cylinder, spring, piston, valve ball, dip tube. Soak component in related chemicals for 24-48 hours, then measure the components’ dimension to check inflation or shrinkage. Finally assemble component into completed product and test its performance. A simplified way is to use trigger spray pump for a few times, leave chemical reserved in trigger sprayers after use. Re-test them after 24-48 hours to check if blockage, leakage or other functionality defect occurs.


Remember to do record during samples test. A check list will be helpful to avoid omission for sample test, and an overall sample test could be a good start to proceed bulk order. As we always say, quality hides in details. If you have any comment or question for sample test, please feel free to contact us.

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