Breast Pump 101: A Beginner's Guide to Breast Pumps, Flanges & Pump Parts
New to breast pumping? You're not alone.
If you're looking at a breast pump for the first time, all the different parts, sizes, settings, and compatibility information can feel overwhelming.
What exactly does a flange do? What is a valve? Do you need a 24 mm flange? How do you know whether it fits? And what should you do when your pump doesn't feel comfortable?
This guide explains the basics of breast pumping in simple terms—from understanding how a breast pump works to choosing the right flange and knowing when your pump parts may need to be replaced.
Let's start with the basics.
What Is a Breast Pump?
A breast pump is a device that uses suction to remove breast milk from the breast.
You can pump milk to:
- Feed your baby with a bottle or other feeding method
- Store milk for later
- Pump when you are away from your baby
- Maintain or increase milk removal when direct breastfeeding is not possible or convenient
There are several types of breast pumps.
Manual Breast Pumps
A manual pump is operated by hand. It is generally simple, portable, and does not require electricity or batteries.
Electric Breast Pumps
An electric pump uses a motor to create suction. Electric pumps are commonly used by mothers who pump regularly.
Wearable Breast Pumps
Wearable pumps are designed to be worn inside a bra, allowing you to pump with greater freedom of movement.
Hospital-Grade or Multi-User Pumps
Some pumps are designed for frequent or intensive use and may be available through hospitals or rental programs.
Remember: a stronger pump is not necessarily a better pump for every mother.
Comfort, proper fit, appropriate settings, and effective milk removal are all important.
Understanding the Parts of a Breast Pump
Although breast pumps can look complicated, most systems use several basic components.
A typical pumping system may look something like this:
Breast → Flange → Connector → Valve → Bottle
For pumps that use tubing:
Breast → Flange → Connector → Valve → Bottle
Tubing → Pump Motor
Backflow Protector →Tubing → Pump Motor
The exact arrangement varies between pump models, but understanding what each part does will make it much easier to choose and replace your pump parts.
1. Flange / Breast Shield
The flange, sometimes called a breast shield, is the part that sits against your breast during pumping.
It surrounds the nipple and creates a seal between your breast and the pumping system.
The flange is one of the most important pump parts for comfort and fit.
A flange that does not fit well may cause discomfort, nipple rubbing, excessive tissue being pulled into the tunnel, or other pumping problems.
The flange has two important areas:
Breast shield:
The wider part that rests against your breast.
Nipple Tunnel:
The narrower part through which your nipple moves during pumping.
When people talk about a "24 mm flange" or "17 mm flange," they are generally referring to the size of the flange tunnel.
2. Insert
An insert fits inside a compatible flange and reduces the diameter of the tunnel.
For example, an insert can allow a larger flange to be used with a smaller nipple.
Instead of purchasing a completely different flange for every size, some pumping systems allow you to use:
Larger flange + insert = smaller effective nipple tunnel
This can give you more flexibility when finding a comfortable fit.
3. Connector
The connector connects the flange to the rest of the pumping system.
Depending on the pump design, the connector may connect the flange to the milk bottle, valve, tubing, backflow protector or other pump components.
Because different breast pumps use different connector designs, compatibility is important when choosing replacement or alternative pump parts.
4. Valve / Duckbill Valve
A valve controls the flow of milk through the pumping system and helps the system maintain proper operation.
A common type is the duckbill valve, named for its shape.
Valves are soft, flexible parts that may wear over time. A valve that is damaged, deformed, or not seated correctly can affect pumping performance.
If your pump seems weaker than before, checking the valve is a good place to start.
5. Bottle
The bottle or collection container receives the milk removed during pumping.
The bottle must be compatible with the pumping system and should be properly attached before pumping.
6. Backflow Protector
This part serve to create a barrier between the milk and the air from the tubing. It is used in some breast pump system to prevent milk going into the the tubing, thus pump motor.
7. Tubing
Tubing connects the pump motor to the pumping assembly on pumps that use tubing.
Not every breast pump uses tubing.
If your pump uses tubing, make sure the tubing is properly connected and free from cracks, holes, or other damage.
8. Pump Motor
This is the part that actually create a vacuum at a set strength and frequency. A side note - Maymom does not make a pump motor. Maymom provides a great selection of pump parts to go with the pump you own for comfortable pumping.
The Most Important Question: What Flange Size Do I Need?
If you're new to pumping, flange sizing can be confusing.
One of the most important things to understand is:
Your nipple size is not necessarily the same as your flange size.
The size printed on a flange refers to the inner diameter of its nipple tunnel at the entry point—not simply the size of your nipple.
The goal is to find a flange that allows your nipple to move comfortably during pumping without excessive rubbing or unnecessarily pulling a large amount of surrounding tissue into the tunnel.
How to Measure Your Nipple
As a starting point, measure the diameter of your nipple before pumping.
When measuring:
- Measure the nipple itself.
- Do not include the areola.
- Measure the diameter across the nipple rather than around it.
- Use millimeters (mm) for the measurement.
For example, you might measure:
Nipple diameter = 15 mm
This does not necessarily mean that a 15 mm flange will automatically be the perfect choice.
Your actual pumping experience matters too.
Nipple movement, swelling, comfort, breast anatomy, and the amount of surrounding tissue drawn into the tunnel can all affect which flange works best for you.
If you are unsure about sizing, a qualified lactation professional can also help assess your fit.
How Do I Know If My Flange Fits?
A good starting point is to observe what happens to your nipple while you are actually pumping.
Signs Your Flange May Be Too Small
You may notice:
- Your nipple rubs hard against the sides of the tunnel.
- Your nipple does not move freely.
- Pumping is uncomfortable or painful.
- Your nipple becomes irritated or swollen.
- Your nipple appears compressed during pumping.
Signs Your Flange May Be Too Large
You may notice:
- A large amount of areola is pulled into the tunnel.
- Excess breast tissue is drawn into the tunnel.
- Pumping feels uncomfortable.
- Your breast or nipple becomes swollen after pumping.
What Does a Better Fit Look Like?
During pumping, your nipple should generally be able to move freely inside the tunnel without excessive rubbing.
Some movement of surrounding tissue can be normal. The goal is not to eliminate all movement of breast tissue, but to find a comfortable setup that works well for your body.
Comfort matters.
If pumping hurts, don't assume that pain is something you simply have to tolerate. Check your flange fit, pump settings, positioning, and pump parts.
How to Use a Breast Pump
If this is your first time pumping, start slowly.
Before Pumping
1. Wash your hands
Wash your hands before handling your pump parts or breast milk.
2. Make sure your pump parts are clean
Clean the parts that come into contact with breast milk according to the pump manufacturer's cleaning instructions.
3. Assemble the pump
Assemble the flange, connector, valve, bottle, tubing, and other components according to your pump manufacturer's instructions.
4. Check the valve and tubing
Make sure the valve is installed correctly and the tubing is properly connected if your pump uses tubing.
5. Position the flange
Place the flange against your breast and position your nipple approximately in the center of the tunnel.
Start Pumping
Begin with a low suction level.
Allow your body to adjust to the sensation, then gradually increase the suction if desired and if it remains comfortable.
More suction does not necessarily mean more milk.
The strongest setting on your pump is not automatically the most effective setting.
Too much suction may cause discomfort or nipple irritation.
Instead, look for a setting that provides effective pumping while remaining comfortable for you.
Use the highest comfortable setting that works well for you—not simply the highest setting available.
Follow the instructions supplied with your particular breast pump for information about its pumping modes and settings.
How Long Should I Pump?
There is no single pumping time or schedule that is right for every mother.
Your needs may be very different depending on whether you:
- Pump occasionally
- Pump in addition to breastfeeding
- Pump when you are separated from your baby
- Exclusively pump
- Are pumping to establish or maintain milk supply
If you are establishing or maintaining your milk supply, a lactation professional can help you determine a pumping schedule appropriate for your situation.
Pumping Should Not Be Painful
Some mothers expect pumping to feel uncomfortable, especially when they are just getting started.
However, significant or persistent pain should not simply be ignored.
If pumping is uncomfortable, check the following:
1. Flange fit
Is your nipple rubbing against the tunnel?
Is too much tissue being pulled into the tunnel?
2. Suction level
Try reducing the suction.
Higher suction is not necessarily better.
3. Positioning
Make sure your nipple is positioned appropriately within the flange tunnel.
4. Pump parts
Check the valve, connector, tubing, and other parts for damage, wear, or incorrect assembly.
5. Get professional help when needed
If pain persists, or if you experience significant swelling, injury, bleeding, or other concerns, consult a qualified lactation professional or healthcare provider.
Your Breast Pump Is a System—not Just a Motor
When a pump does not seem to work as well as it used to, many mothers immediately suspect that the motor is failing.
But the motor is only one part of the system.
The condition, fit, and compatibility of the pump parts connected to the motor can also affect your pumping experience.
For example:
| Pump Part | Why It Matters |
|---|---|
| Flange | Breast and nipple fit |
| Insert | Reduces the flange tunnel size |
| Connector | Connects components of the pumping system |
| Valve / Duckbill | Controls milk flow and helps maintain system operation |
| Tubing | Transfers air between the pump motor and pumping assembly |
| Bottle | Collects pumped milk |
If your pump suddenly seems weaker, check the pump parts before assuming that the motor itself has failed.
When Should I Replace My Pump Parts?
Pump parts that are frequently used can wear over time.
Regularly inspect your parts and replace them when they become:
- Cracked
- Torn
- Stretched
- Deformed
- Damaged
- Difficult to clean
- Loose-fitting
- Less effective than before
Some wear may be difficult to see.
For example, a backflow membrane may become less effective even when it does not appear obviously damaged.
If your pump performance changes:
Check your valves, membranes, tubing, connectors, and other pump parts before assuming that your pump motor has a problem.
Always follow the replacement recommendations provided by your pump manufacturer when applicable.
How Do I Choose Replacement Pump Parts?
Before purchasing a replacement or alternative pump part, check three things.
1. Identify Your Pump Model
First, find the exact model of your breast pump.
Different models from the same manufacturer may use different parts.
2. Identify the Part You Need
Are you looking for:
- A flange?
- An insert?
- A connector?
- A valve?
- A duckbill?
- Tubing?
- A bottle?
- Another replacement component?
Knowing the exact part you need will make finding a compatible replacement much easier.
3. Check Compatibility
Not every breast pump part that looks similar is compatible with every pump.
Always check the compatibility information for the specific part before purchasing.
Flange vs. Insert: What's the Difference?
This is one of the most common sources of confusion for new pumping mothers.
A Flange
A flange includes the breast shield and the tunnel.
It sits directly against your breast during pumping.
An Insert
An insert fits inside a compatible flange and reduces the diameter of the tunnel.
For example:
24 mm flange + insert → smaller effective tunnel
This can give you additional sizing options without requiring a completely different flange for every size.
Can My Flange Size Change?
Yes, the flange size that works best for you may change over time.
Your body can change during pregnancy, after giving birth, and throughout your breastfeeding and pumping journey.
Your pumping needs can also change.
If your current setup suddenly becomes uncomfortable or seems less effective, it may be worth reassessing:
- Your flange fit
- Your nipple size
- Your pump settings
- Your pump parts
- Your pumping technique
The size that worked for you several months ago may not necessarily be the size that works best today.
A Simple Breast Pump Checklist for New Moms
If you are just getting started, don't worry about learning everything at once.
Start here:
Step 1 — Identify your pump
Find the manufacturer and exact model.
Step 2 — Learn your pump parts
Identify the flange, connector, valve, bottle, tubing, and other components.
Step 3 — Measure your nipple
Measure the nipple itself, without including the areola.
Step 4 — Choose a starting flange size
Use your measurement as a starting point, then evaluate the actual fit during pumping.
Step 5 — Start with comfortable suction
Begin with a low setting and increase gradually if comfortable.
Step 6 — Observe your nipple during pumping
Look for comfortable movement without excessive rubbing or excessive tissue being pulled into the tunnel.
Step 7 — Reassess if something doesn't feel right
Pain or poor performance may be related to flange fit, settings, positioning, or pump parts.
Step 8 — Keep your pump parts in good condition
Inspect frequently used parts and replace worn or damaged components.
Need Help Finding the Right Pump Parts?
Choosing breast pump parts can be confusing—especially when you are trying to determine flange size and compatibility at the same time.
Maymom is here to give you more choices.
Maymom offers a wide range of breast pump accessories, including flanges, inserts, connectors, valves, tubing, bottles, and other replacement parts, with options designed to work with a variety of popular breast pump systems.
Whether you need a smaller flange, a different flange style, an insert, or a replacement pump part, start with two questions:
What pump do I have?
and
What part do I need?
From there, you can find the compatible Maymom option that best matches your needs.
You can buy Maymom products on Amazon, Wal-Mart platforms and through its retailers around the world.
Frequently Asked Questions
What is a breast pump flange?
A breast pump flange, also called a breast shield, is the part of the pump that sits against your breast and surrounds your nipple during pumping.
How do I know what flange size I need?
Measure the diameter of your nipple without including the areola, then use that measurement as a starting point. Your actual pumping experience and comfort are also important when determining whether a flange is a good fit.
Is a 24 mm flange suitable for everyone?
No. Flange size is individual. A 24 mm flange may work well for some mothers but may be too large or too small for others.
Can I use an insert with my flange?
If the flange is designed to accept a compatible insert, an insert can reduce the diameter of the flange tunnel and provide additional sizing options. Most likely you will be able to find a Maymom insert that can fit your flange.
Why does my breast pump suddenly seem weaker?
Check the pump parts first. A worn valve, damaged tubing, improperly installed connector, or other part may affect pump performance. Also check that all components are assembled correctly.
Does stronger suction mean more milk?
Not necessarily. A higher suction setting is not automatically more effective and may cause discomfort. Use a comfortable setting appropriate for you and your pump.
Should pumping hurt?
Significant or persistent pain should not simply be ignored. Check your flange fit, suction level, positioning, and pump parts. If pain continues or you have other concerning symptoms, consult a qualified lactation professional or healthcare provider.
Can my flange size change?
Yes. Your body and pumping needs can change over time. If your current flange becomes uncomfortable or seems less effective, reassess the fit.
Are all breast pump parts interchangeable?
No. Pump parts vary between manufacturers and models. Always check compatibility before purchasing a replacement or alternative part.
A Final Note
Every mother and every pumping journey is different.
Finding the right breast pump and the right pump parts may take some trial and adjustment. Comfort, proper fit, and effective milk removal are more important than simply choosing the most common size or the strongest suction setting.
We hope this guide helps you feel more confident as you begin your pumping journey.
Happy pumping!
— Maymom