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Click on a Category of Frequently Asked Questions:
- Availability, Options
- Testing, Quality
Q. What is your normal delivery lead-time for pressure switches?
A. One to two weeks for standard products.
Q. Can you provide custom design switches?
A. Yes. DesignFlex excels in providing custom products. Our manufacturing facilities include die-casting, stamping, injection and compression molding, machining and assembly. We manufacture our own tooling, dies, molds, and fixtures, so turnaround on your custom design is fast!
Q. Are samples available?
A. Yes. We can often send you a variety of samples from our standard product line within two days.
Q. Why are DesignFlex pressure switches unique?
A. DesignFlex switches feature gold inlay contacts, which prevent corrosion and guarantee long life. We also provide a wide variety of housing and port options, and our PSF100A is the only shock and vibration resistant switch available in the world.
Q. What kind of life can I expect from a DesignFlex switch?
A. Under normal pressure and temperature conditions, our switches are rated to perform in excess of 20 million cycles.
Q. Do these products withstand start up vacuum on the pressure side? What is the limit? How are the product specs affected?
A. Any amount of vacuum on the pressure port will not damage the switches.
Q. What is your warranty for pressure switches?
A. DesignFlex warrants that its products will be free from defective materials and workmanship for a period of 12 months from the date of delivery to the original purchaser and that its products will conform to specifications and standards published by DesignFLEX. Any product found to be defective will be replaced or repaired at the sole option of DesignFlex. Our warranty is limited to the foregoing. DesignFlex disclaims any warranty of merchantability or fitness for intended purpose.
Q. Do you charge for application engineering assistance?
A. Not for standard products. Our engineers have years of experience in applying pressure and vacuum switches for all types of applications. They are always available to answer your questions, and will make sure you have the right product for the job.
Q. What are the materials of the set-screws, contact arms, terminals and the compression springs used in the products?
A. Springs and screws are type-302 stainless steel. The contact arms are spring-tempered phosphorous-bronze with a gold inlay at the contact point, and the terminals are half-hard brass. Other materials are available upon request.
Q. What is the factory setting tolerance (non-adjustable products) for the different series?
A. Non-adjustable switches have a factory tolerance of +/- 20% of the set point. There are exceptions to this rule that our sales department can explain. For example, the 0.5" version of the PSF100A and PSF101 are defined as differential switches that will actuate somewhere between 0.2" and 0.5" h2O. PSF103, adjustable switches, also have a factory tolerance of 20%, and the PSF102s generally carry a 10% tolerance except for the lowest settings, which are +/- .1" on the .1' to .5" model.
Q. Can you provide switches with lower tolerances than those listed in your catalog?
A. Yes. Call our engineers for assistance.
Q. What is the definition of proof pressure? What is the effect at and above the value?
A. It is the maximum amount of pressure allowed without adversely affecting the set point of the switch. If it is exceeded, then the set point may be permanently changed due to the distortion of one or more of the internal parts or the diaphragm could be damaged.
Q. What are the deadbands (on-off differential) of the products, and are they adjustable?
A. The hysteresis of our PSF103 and PSF109 switches are not selectable. The reset point is typically from 50% to 75% of the set point. Consult us for tighter specifications.
Q. What is the repeatability of the products within adjustable range, within proof pressure? Is it defined as a % of the range or the set point?
A. The switch will repeat within the 20% tolerance from the set point, so long as the customer does not exceed the other specifications, like proof pressure, temperature, voltage, current, etc.
Q. What is the effect of shipping on set point shift?
A. We set our switches to a tighter than +/- 20% tolerance to compensate for any shifting that may occur during shipping.
Q. Is there any long-term set point drift that customers should be aware of?
A. The first actuation on switches with a snap switch, after a long period of time, may be higher than the following actuations; which will be back to the normal setting.
Q. Are there any agency approvals for the product line (not just the switch component)?
A. We carry U.L. approvals (File #E41523) and a variety of snap switch approvals.
Q. Is the product marked with the electrical rating of the switch? Can it be marked?
A. Series 103 and 109 products are marked and others can be upon request.
Q. Are any electrical termination options available, besides the 3/16? (1/8" or ¼")
A. We have some .25" terminals on our PSF103 and PSF109 switches. The PSF101 and PSF102 have options for soldering to a circuit board.
Q. What changes are made to the product for the special operating range of -46°F to 205°F?
A. We can make the switches out of various housing materials, such as polyetherimide, or PPS resin, and we would usually go to our Teflon diaphragm. If you want to be assured the switch will operate at the temperature extremes, then we would perform actual environmental testing in our thermotron chambers.
Q. On the differential pressure units, what are the working pressures?
A. We consider our proof pressure as the working pressure.
Q. What is the current (amps.) for 120 VAC neon lamp load?
A. The current through the switch, when in series with a neon lamp and a resistor (20K to 30k typically), will not destroy the contacts. That is why we allow its use. The actual current depends on the resistor, and the lamp, typically under 4mA.
Q. Ranges on 103 series starts at 2" wc. Is this on rising or falling pressure?
A. 2" h2o on increasing pressure. These de-actuate between 0.5" and 1" h2O.
Q. With the PSF 103, why do different ranges have different electrical ratings? And why no 25Amp. rating?
A. The current ratings depend on the snap switch that goes into the product. We design the highest possible rated snap switch into the lowest possible pressure range, then use a spring to increase the range of the switch from that pressure starting point. We do have a 25Amp snap switch available, but we only use it when customers request it.
Q. How does the solid-state relay connect to the standard product (electrically)?
A. It can be connected for normally open, or normally closed. A wiring diagram is sent with every relay we sell.
Q. What is the accuracy of the pressure gauge used to factory set our units?
A. We use various inclined manometers, vertical manometers, magnehelic gauges, and two high pressure gauges, that all have different % accuracy. Using our calibrated hook gauge, we calibrate our inclined manometers to ±½% of full scale, and the magnehelics are ±3% of full scale.
Q. Are products cycled prior to being factory set?
A. Not unless the customer requires it, which then dictates a special listing with a special routing.
Q. Do you have any qualification test data on the products? (i.e. life at different pressures, electrical load, ambient temperatures etc. )
A. We do have that information in a raw form, in life test data notebooks in the engineering area. Some of it is general testing and we have performed special testing prior to being awarded certain contracts.
Q. Are there any instructions or warnings for installations and maintenance?
A. Installations should be done in accordance with U.L. requirements. (i.e. Use insulated connectors whenever using high voltage. Our pressure switches are simple devices and do not generally require instructions.)