Parts & Pieces

Your pump came with a lot of accessories… what are they all and what do they do? How do you assemble them? How often do you replace them?
*Your pump parts might look a little different, but most have similar functionality. Check your user manual if you want product-specific information!


This is the FLANGE, otherwise known as a “breast shield.”
The cone of the flange hugs the breast tissue and funnels the areola and nipple toward the flange tunnel for milk expression. It should fit snuggly on your breast and be sized to suit the diameter of your nipple. A sizing guide is shown below, or request a consultation using “Get Help” from the menu bar above.
During pumping, the nipple should move freely within that tunnel, without your areola (The darker area around your nipple) being sucked into the tunnel, and without the nipple itself rubbing along the sides of the tunnel.
These should be replaced if they crack or warp.

Pumping shouldn’t hurt. Finding your correct flange will help you pump comfortably and express milk effectively.

Measure your nipple by holding a metric ruler under the thickest part of your nipple. Use the chart above to estimate your flange size. Measurements should be taken BEFORE pumping. Then, while pumping… take a look at your nipple. The nipple will swell a bit while pumping but the sides of your nipple shouldn’t rub the sides of the flange tunnel (too small) and shouldn’t pull too much of your areola inside the tunnel (too large.)

IMPORTANT NOTE: Recent clinical research suggests that a flange may be a better fit if it’s close to your nipple width (or within 1 millimeter) So I like to give you a range. For example, if your nipple measures 16mm, consider a flange in the 17-19mm range! You want to have NO pain, strong milk sprays, and empty fully.

Alternative flange styles provide added comfort, and are a great consideration for women with elastic nipple tissue. Here are a few favorites:

Lacteck Baby Motion Flange
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Lacteck silicone flanges are soft and flexible, with a small portion in the tunnel that moves to simulate baby’s tongue ripple during nursing. These flexible flanges are helpful if you have to do breast compressions and massage while pumping .

PumpinPals Flanges
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PumpinPal flanges are angled and ergonomically designed for comfort. There is no sharp edge between the flange cone and tunnel, a source of discomfort in your standard issue flange. They also come in a multi-pack so you can experiment with different sizes.

BeauGen Flange Cushions
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These inserts provide added comfort while pumping. Made of extremely soft flexible plastic, they line your flange and provide a secure fit to your breast. They are also great to use if you are between flange sizes. A must-have for elastic nipples and Elvie/Willow users!

There are also many quality “knock-off” brands on Amazon if your pump company does not carry your flange size. Check out my helpful list HERE.

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Connectors connect the flange/shield with the bottle. Some pumps have a separate flange and connector, some are connected as one piece. Often, the valve will connect here. In the yellow hub pictured here, there is a floppy center piece inside that acts as a valve and back-flow protector in one. This feature is unique to that style pump.
Make sure all parts are clean and dry when you attach them, so you get a snug fit, in order to create a good vacuum seal for suction.
Connectors should be replaced if they crack or warp. The ones in the lower left are designed for Spectra bottles so you can use alternative flanges and are available HERE.


Your valves are arguably the most important part of your pumping accessories. They control the suction. When they stretch, weaken, or tear in any way, you’ll pump less milk. Exclusive pumpers should change their valves every month. Occasional pumpers should change valves every 3 months.
Some pumps have duckbill valves (top left), some have a two-piece valve-and-membrane unit (bottom). In that case, you often just have to replace the floppy white membrane. Some pumps have a “hub” connector with a membrane/valve piece inside (top right), in which case you need to buy a whole new hub if you notice your pump extracting less milk. Those are not interchangeable with other types of valves.

Backflow Protector

You might or might not have a backflow protector. There are two types of electric pumps: Open system and Closed system. CLOSED system pumps have back-flow protectors that do not allow milk to enter the tubing, so they are perfect for frequent pumping and multiple users (like hospital pumps). Wash these if they get moisture inside them and thoroughly dry before reassembling. NO NEED to wash your tubing with a closed system pump. OPEN system pumps do not have a backflow protector and milk can potentially get inside your tubing and into your pump itself. Users should avoid a lot of movement while pumping and stop the pump if milk does get into the tubes.
Backflow protectors can stretch out and should be replaced every 3 months.

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Pump bottles usually come in two styles: standard size neck and wide neck, and two sizes: usually 5oz and 8oz. Unless you are an over-supplier, sticking with the smaller bottle is just fine. It’s typical for moms to pump less than that amount in one sitting and breastmilk-fed babies usually don’t take more than 5oz in one feed anyway. You don’t have to feed from the bottles you pump into. For example, I pump into my spectra bottles and then empty the milk into medela for feeding because I prefer those bottles. When baby has a bottle preference, it’s usually the nipple style, so try different bottle nipples until you find one that baby latches well to!


Tubes connect your pumping accessories to your pump. Some tubes have small plastic connector pieces at the ends, some do not. Closed-systems pumps do NOT require you to ever wash the tubing. For open-system pumps, wash tubing if moisture or milk gets inside.
Wash by soaking hot soapy water, then rinse with clean water. Whip over your head like a lasso (not kidding, it works!) Then, run your pump with tubes only attached for 3-4 min.
Should be clean and dry!
Tubes should be replaced if you notice cracking, extreme loss of suction, or mold.

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