Tube
Bending radius
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Frequently Asked Questions for Tube Series
Basically, you can use any tube fitting from any series as long as the tube diameter is right.
*For Compression Fitting series, both the tube O.D. and tube I.D. must be applicable.
Please check the specification and characteristics of each tube fitting and tube such as fluid medium, maximum operating pressure, operating temperature range, materials of parts and so forth to select the most suitable ones for your applications.
Example: For Tube Fitting PL6-01, a tube with Φ6 mm O.D. (UB0640..., NA0640..., etc.) is suitable.
Please utilize a search feature on the product list page of PISCO website to narrow down the suitable product by specifying detailed conditions such as specifications, characteristics, and materials of parts, etc.
If the tube diameter doesn’t match, we have a reducer, which we call "Unequal Plug-in Straight" (PGJ), that can change the tube diameter to fit a tube fitting of your choice. Please contact PISCO sales office in your region for details.
Also, please keep in mind the following.
<Cautions>
Since the flame-retardant outer cover of Anti-spatter Tube must be peeled off the tip for connection, the outer diameter (O.D.) of the inner tube, not the inner diameter (I.D.), is specified in the Model Designation.
Although the tube O.D. will be larger with the flame-retardant cover included, please select the tube fitting based on the O.D. of the inner tube.
Example: For FB0640-20, choose a tube fitting with an applicable tube O.D. of Φ6 mm (such as KC6-01).
*Be sure to peel off the outer cover when inserting the tube into the tube fitting. Otherwise, the tube may burst.
FB0640-20
When inserting Vacuum Tube (UD) into Push-in Fitting (excluding Minimal Fitting and Compression Fitting), be sure to use Insert Ring.
We have Hand Valve and Ball Valve, which are shut-off valves, to stop the air. We also have Cap (PPF) that plugs the tip of an unused tube.
Similar to PISCO Push-in Fitting, simply insert the tube into Cap. This will prevent airflow.
Please check the color transparency comparison of PISCO tubes.
The related FAQ
Nylon Tube (NA) or Soft Nylon Tube (NB) can be used for heat medium oils (with some conditions*).
More expensive fluoropolymer tubes such as SFT and SET series are available as well.
Oils are composed of various elements and may require evaluation on actual operating conditions.
The related FAQ
Using PISCO tubes is basically recommended.
*Please see the question, "Are PISCO products compatible with tubes or tube fittings of other brands?”
Please make sure that the tube's cutting plane is right angled and three is no scratches, stain or foreign substances present on the tube.
Tubes for push-in fittings of other brands can basically be inserted into PISCO Push-in Fitting as long as the outer diameter matches (with some exceptions). That said, since PISCO Push-in Fitting is designed to seal around the tube (using seal rubber such as an elastic sleeve to seal the outer diameter of the tube), a tube with an imprecise outer diameter will be difficult to insert into or disconnect from the tube fitting or cause air leakage.
We recommend using PISCO tubes with PISCO Push-in Fitting series whenever possible.
When using tubes of other brands, please make sure that the outer diameter tolerances of tubes listed in the table below are met.
Tube O.D. Tolerance
| mm size | Nylon tubes | Polyurethane tubes |
|---|---|---|
|
φ1.8 mm |
― |
±0.05 mm |
|
φ2 mm |
― |
±0.05 mm |
|
φ3 mm |
±0.1 mm |
±0.15 mm |
|
φ4 mm |
±0.1 mm |
±0.15 mm |
|
φ6 mm |
±0.1 mm |
±0.15 mm |
|
φ8 mm |
±0.1 mm |
±0.15 mm |
|
φ10 mm |
±0.1 mm |
±0.15 mm |
|
φ12 mm |
±0.1 mm |
±0.15 mm |
|
φ16 mm |
±0.1 mm |
±0.15 mm |
| Inch size | Nylon tubes | Polyurethane tubes |
|---|---|---|
|
φ1/8 |
±0.1 mm |
±0.15 mm |
|
φ5/32 |
±0.1 mm |
±0.15 mm |
|
φ3/16 |
±0.1 mm |
±0.15 mm |
|
φ1/4 |
±0.1 mm |
±0.15 mm |
|
φ5/16 |
±0.1 mm |
±0.15 mm |
|
φ3/8 |
±0.1 mm |
±0.15 mm |
|
φ1/2 |
±0.1 mm |
±0.15 mm |
|
φ5/8 |
±0.1 mm |
±0.15 mm |
First, please check the product name (and if you have already made a choice, its model code). Also, check the proper name of the chemical to be used.
Then, check the chemical-proof properties of the materials used in your chosen product via the following link, "Chemical-proof properties".
Vacuum Tube UD and Soft Polyurethane Tube UC are flexible. These tubes are suitable for compact piping that requires a small bending radius. (*Please note that Vacuum Tube UD is not ideal for high pressure applications.)
Contrarily, Fluoropolymer (PFA) Tube SFT, Fluoropolymer (FEP) Tube SET, and Anti-spatter Tube FB are hard.
Comparison of tube bending radius
[Video] Flexibility comparison of PISCO tubes (in Japanese only)
Please check the specifications of each tube in the digital catalogs or product pages on PISCO website.
Please make an inquiry for tube samples to PISCO sales office in your region.
For PISCO Push-in Fitting, it is possible as long as the outer diameter of the tube is the same.
However for Barb Fitting and Compression Fitting, both the inner and outer diameters of the tube must match those of the tube fittings for connection.
PISCO products are intended for indoor use in principle, and outdoor use is not covered under the warranty. Please refer to the following table for the characteristics of tube materials.
Since the tubes are greatly affected by operating environments, periodic inspections and replacements are needed when used outdoors.
| Material | Tube type | Weatherability level | Operating temperature range* |
|---|---|---|---|
|
Polyurethane |
UB, UC, etc. |
Weatherability can be affected but at a usable level |
-20 to 70℃ (UB) |
|
Nylon |
NA, NB |
Weatherability can be affected but at a usable level |
-20 to 100℃ |
|
Polyolefin |
CTA, CTB |
Weatherability is easily affected |
-15 to 80℃ |
|
Fluorine (Fluoropolymer) |
SFT, SET |
Weatherability is less likely to be affected |
-65 to 260℃ |
|
PVC (polyvinyl chloride) |
FB |
Weatherability is less likely to be affected |
-15 to 90℃ |
*) When the fluid medium is air. No freezing.
As for tube colors, darker colors, such as black, are more resistant to ultraviolet rays than lighter colors of clear types.
Outdoor tubes may deteriorate faster than indoor tubes due to temperature, humidity, dust, and ultraviolet ray exposure. Please make your decision with this possibility and its associated risks in mind.
Whether water is allowed depends on the model. For the standard PISCO Push-in Fitting, water can be used as long as the conditions are met. The following are the conditions to use water as a fluid medium.
1. Make sure that the surge pressure, which is the temporary increase in pressure when a valve is closed, remains at or below the maximum operating pressure.
2. General tap water in Japan is usable. Since other types of water may not meet our specifications in the same way, please evaluate PISCO products under actual operating conditions and decide whether to use them.
3. Use Insert Ring, a stainless steel insert that provides internal support for the tube.
Use of Insert Ring is recommended to prevent tube contraction. Prolonged water use in the tube can cause the tube to contract, making it prone to coming off or leaking.
You can see the fluid (liquid) in the transparent or clear type color tubes. [Darker color tubes are not suitable for checking the fluid (liquid) inside the tube.]
Even if the fluid (liquid) is colorless and transparent, its flow can be easily seen if the air (air bubbles) is mixed in.
*) Fig. 1 (The visibility of the colored water depends on its color strength.)
However, even if the liquid is flowing, you need to closely check the inside of the tube, regardless of its color or the color of the liquid, if the tube is filled with liquid [without air (bubbles).]. *Fig. 2
Small air bubbles may adhere to the inner surface of the tube after the liquid has continued to flow for a while, allowing you to see for the presence or absence of the liquid.
Fig. 1
Fig. 2
Transparent or clear type color tubes that can be used with water
*) Please check the safety instructions of each tube before using liquid.
The related FAQ
Basically no.
A tube that is too soft to withstand being squeezed by one's fingers will be difficult to insert into Push-in Fitting. Even if it could be inserted, it would have low pull-out strength and could easily come off.
PISCO Vacuum Tube (UD) is an ultra-soft polyurethane tube that can be squeezed by one's fingers. However, it can be inserted into PISCO Push-in Fitting when used with Insert Ring (a stainless steel insert that provides internal support for the tube).
Both SFT and SET have excellent chemical resistance and can be used in various fields including chemicals, food, medicine, and semiconductors. The main difference between the two is the operating temperature range.
[SFT] Fluoropolymer (PFA) Tube
-65℃ to 260℃
*) Excels in heat resistance
[SET] Fluoropolymer (FEP) Tube
-65℃ to 200℃
They have roughly the same bending radii (hardness) and chemical resistance. For the specific numerics, please refer to the chemical proof properties, product pages or digital catalogs on PISCO website. FYI, SET is less expensive than SFT and more affordable.
*) If the fluid medium is other than air, such as water or chemicals, be sure to read the safety instructions on PISCO website, and check the compatibility between the to-be-used chemicals (components) and the tube with the "Chemical-proof properties" or "Chemical Resistance Chart".
The maximum operating pressure varies by tube type. It is 1.0 MPa for the general Polyurethane Tube (UB type) and 2.0 MPa for Nylon Tube (NA type). For other tube types, please refer to PISCO catalogs or product pages on PISCO website.
*) The above-mentioned maximum operating pressure is measured at 20℃ and 65% RH. As proof pressure changes according to temperature, please refer to "Burst Pressure Curve” in PISCO catalogs or on PISCO website.
PISCO Nylon Tube has excellent pressure resistance and is designed for general piping applications.
Nylon Tube (NA) has the maximum operating pressure of 2.0 MPa (at 20℃ and 65% RH). It comes in a wide variety of sizes (millimeters and inches) and colors. On the other hand, Soft Nylon Tube (NB) has the maximum operating pressure of 1.3 MPa (at 20℃ and 65% RH), which is lower than NB type, but it is more flexible and easier to bend for piping.
When inserted into the tube, Insert Ring suppresses the tube’s deformation due to changes over time. It also prevents leakage and detachment of the tube.
Be sure to use Insert Ring in the liquid (such as water) piping or when inserting a soft tube into Push-in Fitting.
How to insert Insert Ring
Basically, please choose Insert Ring with a model code that matches the numbers of the tube model code.
[Example] Tube model code UB0640 matches Insert Ring model code WR0640.
However, some tube types have millimeter sizes that also correspond to inch sizes. Please check the corresponding sizes (Tube size chart) in PISCO catalog.
PISCO Insert Ring (WR) is specifically designed and developed for use with PISCO tube series.
Using PISCO Insert Ring with other brand’s tube may cause insertion failure or detachment of the tube even if the tube size matches, because of a different tube tolerance.
Because UBT uses ester TPU (thermoplastic polyurethane), the tube has low water resistance and is susceptible to hydrolysis, which may result in water leakage due to material deterioration.
The related FAQ (Tubes)
TPU is Thermoplastic Polyurethane. It is a kind of plastic generally called urethane rubber or urethane resin.
Thermoplasticity refers to the characteristics which material becomes pliable or moldable above a specific temperature and returns to a solid state upon cooling
There are 2 kinds in what is called urethane; ester and ether.
TPU(ether)
Example ： UB, UC, UBS, UD, UQ, UCQ, UL, etc.
Elastomer made by reaction of ether and diisocyanate. High water resistance.
TPU(ester)
Example ： UBT, UE
Elastomer made by reaction of ether and diisocyanate. High mechanical strength, but is susceptible to hydrolysis.
Hydrolysis is a chemical reaction caused by water in which a chemical compound is broken down.
For example, exposure to water accelerates the deterioration of plastics and rubbers and the reduction in their strength.
Ester polyurethane resin used in polyurethane tubes (including Dedicated Polyurethane Tube UBT and Anti-static Tube UE) is more susceptible to hydrolysis than ether polyurethane resin used in Polyurethane Tube UB or polyolefin type resin.
PISCO tubes* have printed cut marks at 500 mm intervals to help with cutting the tube.
*) Tube UB0180, UB0212, CTA, CTB, SFT, and SET have no cut marks.
Requests for cut mark interval changes or no printed cut marks can be accommodated as a special order. (The minimum order length is 500 m per tube)
Please contact PISCO sales office in your region for special orders.
It is an additive called a plasticizer that makes the tube flexible. The plasticizer migrates to the surface of the tube, where they crystallize and ooze out.
This phenomenon is called blooming.
This blooming phenomenon occurs inevitably when an additive is used in nylons.
It does not affect the tube’s performance including its pressure and chemical resistance. However, in the long run, the tube’s flexibility tends to deteriorate.
The white powder oozes out onto the surface of the tube over time due to the tube's inherent property, which is the migration of the additives mixed in the materials. The tube's performance remains unaffected.
You can use the tube as it is if you don't mind the white powder.
The white powder will come off just by lightly wiping off with a waste cloth or rag. Please be careful not to rub the tube too much, as this will cause the print to fade.
The related FAQ
Hot water-resistant Tube WA series was discontinued in 2009.
The substitutes for WA are Nylon Tube NA and Soft Nylon Tube NB series.
The vacuum tube "NC" was discontinued in 2010.
The current equivalent is the vacuum tube "UD".
The material has been changed from nylon to polyurethane.
Inquiries about this product
It is also possible to suggest products suitable for various conditions such as applications and functions. Please feel free to contact us or visit the nearest sales office.
The following are frequently asked questions. Please check before making inquiries.