Teflon PTFE Plastic Ball
Model:KXT PB150
Chemically inert PTFE balls for check valves, ball valves, metering and diaphragm pumps and light-load bearings: 1.5 to 350 mm (1/16 to 14 in), virgin or glass, carbon, graphite and bronze filled, precision grades 0-III, service from -269 °C to +250 °C.
PTFE Ball · KXT PB150
PTFE Balls for Check Valves, Pumps and Bearings — 1.5 to 350 mm
A PTFE ball is the moving sealing element in a check valve, a ball valve or a pump check seat. It is chosen where the fluid would corrode a stainless ball, where the ball must not gall or scratch the seat, or where the ball's weight decides how fast the valve reacts. Kaxite moulds and machines these balls from 1.5 to 350 mm, in virgin PTFE and in glass, carbon, graphite and bronze filled grades.
Ø1.5–350 mm · 1/16–14 in · grades 0 / I / II / III · −269 to +250 °C · virgin & filled
Properties
| Density | 2.16 g/cm³ |
|---|---|
| Hardness | 50–65 Shore D |
| Compressive yield strength | 7–30 MPadepends on filler |
| Young's modulus | 670 MPa |
| Coefficient of friction | 0.12 |
| Water absorption, 24 h | 0.02 % |
| Linear thermal expansion | 145 ×10⁻⁶/°C |
| Thermal conductivity | 0.23 W/(m·K) |
| Volume resistivity | > 10¹⁶ Ω·m |
| Magnetic behaviour | Diamagnetic |
Size and grade
| Metric range | 1.5–350 mm |
|---|---|
| Inch range | 1/16–14 in |
| Precision grades | 0, I, II, III |
| Virgin grade | Natural white |
| Filled grades | Glass, carbon, graphite, bronze |
| Colour grades | Made to order |
| Special sizes | Machined to drawing |
What the ball actually does
A check valve is a seat with a ball sitting on it. Forward flow lifts the ball off the seat and the line opens; when flow stops or reverses, the ball drops back and the seat seals. The same element appears in ball valves, as the check ball in metering and diaphragm pumps, and as a low-load bearing ball.
That duty defines what the ball has to be. It must seal on a narrow contact line, move at the pressure the pump can produce, and survive the fluid without swelling, corroding or galling. PTFE does the last two better than any metal and the first one differently: it conforms to the seat instead of relying on two hard surfaces lapping together, which is why a PTFE ball can seal against a damaged seat that a steel ball would leak past.
Weight matters more than most people expect
PTFE has a density of 2.16 g/cm³ against roughly 7.9 for 316 stainless. The same diameter weighs about a quarter as much, so the ball lifts at a lower flow and drops back faster when the flow stops. On a dosing pump that is the difference between a crisp check and a dribble.
The trade-off is on the other side of the same property. A light ball is easier to hold off its seat by a pressure pulse, and it can chatter in a high-flow line where a heavier ball would sit still. Where the valve has to be quiet, the usual answers are a denser filled grade, a spring-assisted seat, or a change of seat geometry — not a larger ball.
Grades: what the filler changes
| Grade | What it changes | Where it belongs |
|---|---|---|
| Virgin PTFE | Best chemical resistance and purity; softest, creeps most | Aggressive chemicals, food and pharma lines, laboratory valves |
| Glass filled | Higher compressive strength and wear resistance | Pumps with abrasive or high-cycle duty |
| Carbon or graphite filled | Lower friction, better creep resistance, conductive | Dry-running or high-cycle seats, static dissipation |
| Bronze filled | Highest strength and thermal conductivity | Mechanical duty where the fluid is not aggressive |
| Coloured | Identification only | Where a size or grade must be visible on the bench |
The filler raises compressive yield from the bottom of the 7–30 MPa band towards the top, and it does so at a cost: glass and bronze are abrasive to the seat, and bronze is not chemically inert. A filled ball in an aggressive fluid is a corrosion problem waiting to happen; a virgin ball in a high-cycle pump seat is a wear problem. Matching the grade to the duty is the whole decision.
Ball, seat and clearance
- The seat does the sealing. Ball roundness and surface finish matter, but a leaking valve is usually a damaged, dirty or mismatched seat.
- Match the seat angle. A ball designed for a 45° seat will not seal reliably on a 30° one; send the seat drawing with the enquiry.
- Leave room for expansion. PTFE expands about ten times more than steel, so the guide clearance has to allow for it or the ball will bind when the line warms up.
- Keep debris out. A strainer upstream is cheaper than the pump damage a held-open check ball causes.
- Do not use the ball to compensate for a worn housing. An oversized ball deforms and takes a set, and the valve leaks again within a few cycles.
Size and precision grade
Standard balls run from 1.5 mm to 350 mm, or 1/16 in to 14 in, and are sorted into precision grades 0, I, II and III. The grade controls diameter tolerance and sphericity, which in turn decide how well the ball seats and how consistently it moves. Tell us the grade your valve was designed around, or send the seat and housing drawing and we will match the ball to it rather than to a catalogue size.
Balls are moulded in the common diameters and machined for special sizes, which is why an imperial or worn size is usually a drawing job rather than a compromise. The same stock is used for our PTFE rod range, so material and grade can be kept consistent across a rebuild.
Where these balls are used
Check valvesChemical dosing and transfer lines where a metal ball would corrode.
Metering and diaphragm pumpsSuction and discharge check balls that must seat quickly.
Ball valvesCorrosive media where the ball is the wetted sealing element.
Volume displacementBalls that displace a fixed volume in chemical baths and dosing vessels.
Light-load bearingsBall transfers and low-speed supports that must not mark the product.
Metal-free assembliesLaboratory, pharmaceutical and food equipment where metal cannot be used.
Most of these are replacement parts rather than new designs: a valve is rebuilt and the ball is the cheapest component to change. If that is the case, send the failed ball with the seat — the wear pattern tells us whether the grade, the size or the seat caused the failure, which a diameter measurement alone cannot. The rest of the range sits in our PTFE ball category and in PTFE parts.
What to send with the enquiry
- Diameter, or the seat drawing if the size is not standard.
- Precision grade, if the valve spec calls for one.
- Grade: virgin, glass, carbon, graphite or bronze.
- Media, concentration and temperature — the three that decide the grade.
- Quantity, and whether it is a trial or a scheduled rebuild.
Prototypes and small rebuild quantities are normal work; both run through the same Ningbo workshop. Send the details through the inquiry form and technical sales replies within 2 business hours.
Questions buyers ask before the first order
- What is a PTFE ball used for?
- It is the moving sealing element in a check valve or ball valve, the check ball in a metering or diaphragm pump, and a light-load bearing ball. It is chosen where the fluid would corrode a stainless ball, where the ball must not gall or scratch the seat, or where low weight matters.
- Why use a PTFE ball instead of stainless steel?
- PTFE is inert to most chemicals, does not corrode or gall, and has a density of 2.16 g/cm³ against 7.9 for 316 stainless, so the same diameter weighs about a quarter as much. The lighter ball lifts at a lower flow and seats faster. The trade-off is much lower strength and stiffness, so seat design and pressure have to respect that.
- What sizes are available?
- Standard sizes run from 1.5 mm to 350 mm, or 1/16 in to 14 in. Balls are sorted into precision grades 0, I, II and III. Special diameters are machined to drawing, so an imperial or worn size can be matched rather than approximated.
- Which filler should I choose?
- Virgin PTFE where chemical resistance and purity matter most; glass filled where the ball needs more compressive strength and wear resistance; carbon or graphite filled where lower friction and better creep resistance matter; bronze filled where strength and thermal conductivity dominate and the fluid is not aggressive. Colour has no technical meaning on its own.
- Can PTFE balls be used at high temperature?
- The material serves from −269 °C to +250 °C, but the practical limit in a valve is set by the seat, the spring and the differential expansion between ball and housing. Above about 250 °C, PEEK, ceramic or metal balls are the correct choice.
- Why does a PTFE ball leak?
- Almost always because of the seat, not the ball: a damaged or dirty seat, a seat angle that does not match, debris holding the ball off its face, or a housing that distorts the ball under load. A ball that is out of round or below its precision grade will also fail to seal on a narrow seat.
Send the diameter — or the seat drawing
Media, temperature and quantity are enough to choose the grade. We will match the ball to the valve, not to the nearest catalogue size.
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Contact Info
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Address
No. 432 Zhenhai Middle Road, Luotuo Street, Zhenhai District, Ningbo City, Zhejiang China
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