Download the Model 640N datasheet (pdf version)

The 640N Fail-safe Ohmmeter
The 640N fail-safe igniter tester is ruggedised, water-resistant, portable and has been specifically designed for ultra-safe resistance testing on explosive devices (i.e. Tomahawk Cruise Missile squibs, igniters, flares, detonators). The 640N case is waterproof when closed to a depth of 3 feet. The 640N also floats in water. It can be operated outside in direct rain, as it has silicon rubber boot seals over all switches.

Fail-safe Design - Built-in 'Can't Fail' Life Saving Features
There are a variety of critical military, aerospace and industrial applications which utilise squibs and other blasting devices. In each case, it is extremely important that these devices detonate when required. It is equally important that these devices do not detonate while being tested for coil integrity. To this end, each instrument is equipped with redundant, dual fail-safe current limiting resistor network circuitry to ensure that the instrument test currents cannot exceed the specified amount. Even in the unlikely event of a worst case component failure, the output current limiting network is still in effect.

Naval Ordnance Approved for the Standard Missile
The US NAVAL ORDNANCE CENTRE Safety Board has approved the 640N for use on the NAVY Standard missile. The 640N Igniter Tester safety features and design make it ideal for a variety of electronic explosive device verification requirements (EEDs). The limited access (one use at a time) external connection port on the 640N also makes it physically impossible to simultaneously connect the AC/DC Charger while measuring with the test leads. Whether charging the Ni-Cad batteries or measuring a squib's resistance, there is only one connection port. The 640N operator can connect the AC/DC battery charger to the 640N limited access connection port for recharging the Ni-Cad batteries thus mechanically blocking access for the measuring sense leads. When measuring, using the sense leads, the same limited access connection port then blocks any battery charger connection.

Faraday Cage provides Electronic Noise Immunity, EMP and Static protection
The 640N electronics are encased in a shielded Faraday cage (all to chassis ground) to provide additional electronic noise immunity, Electromagnetic Pulse (EMP) and electrostatic discharge (ESD) protection.

Verify the 640N milliampere current output - Onboard milliammeter and Test resistors
The 640N Igniter tester comes with a SIMPSON tm DC millammeter built into the 640N Function Test Section. The built-in analog milliammeter measures the 640N test current and spans from 0 to 10 millamperes fullscale. This lets the 640N user truly verify that the 640N test current is at "SAFE" levels, just prior to measuring squib resistance. See the 640N diagram below for a more detailed view of the FUNCTION TEST SECTION and the test resistors.

Download the 640N Feature Diagram (pdf version)

1. Calibration/Maintenance access screws, Easily covered with a tamper proof seal or sticker.
2. Purge Valve - Provides Air Pressure Equalization to open the 640N case after a transit involving an altitude change.
3. Handles - see item #1 then lift for calibration access.
4. Single Access Notched Connector - for either test lead hookup or connection to the battery charger. With only one connector to the outside world, it is physically impossible to do both at the same time.
5. Milliammeter for measuring actual 640N test current (0 to 10 milliamperes fullscale). Use of the Meter (+) panel jack and Common panel jack (-) in the FUNCTION TEST SECTION with the 640N test leads provides the analog millammeter - 640N test current measurement connection.
6. Minus sign - indicates low battery levels , it's time to plug-in the battery charger (completely safe).
7. Fuse Access - for general operation .
8. Padlock Hole - Provides added security especially during transit.
9. Battery Charger Storage Area - For storing the battery charger, cord and connector.
10. Input jack - Plug into the 640N Ohmmeter meter test lead. Use the red banana jack.
11. Input jack of 0.1 ohm test resistor for checking the zero accuracy (low end of scale) of 20 ohm range.
12. } 10 ohm and 1000 ohm test resistors for checking the
13. } mid-scale functionality of the 20 ohm and 2000 ohm range.
14. Input jack for connecting the 640N Ohmmeter common test lead (plug-in black banana jack).
15. } 100 Kohm, 1.0 Megohm, and 1.9 Megohm test resistors for checking the mid-scale functionality of the
16. } 200 Kohm and 2.0 Megohm ranges of the 640N . Custom Test Resistor values are available depending
17. } upon the version - contact Permac's Sales Department to discuss your requirements.
18. Water Resistant O-ring seals in lid & under the front plate.
19. Tight Squeeze Flip Latch Area - waterproof seal (closed).
20. Resistance Ranges - 20 Ohm, 2000 Ohm, 200 KOhm and 2.0 megohm ranges - silicone rubber boot seals provide a water-resistant switch cover. LED indicates the selected range.
21. Power On or OFF/Charging Switch.
22. Beveled Display Hood and Super Bright LED Display readable in sunlight.
23. Test leads stored in the rim of 640N lid.

No Hazardous Mercury Batteries
The 640N does not use hazardous mercury batteries like those in older igniter testers. All 640N's are battery powered with a heavy duty rechargeable Ni-Cad pack for portability purposes. A 120 VAC powered battery charger is standard.

It floats in water, and can be operated in direct rain

Polyurethane Epoxy Coated Circuit Board and More ...
A common question we get from evaluating safety engineers is "What sort of electrical and mechanical measures are taken with the AMPTEC 640N to prevent an internal loose wire, metal screw, or washer inside from floating around and shorting the battery output to the terminal output posts?". The ohmmeter's output posts are insulated inside the unit with heat shrink tubing covering any of it's conductive surfaces. The entire PCB (except for the calibration trim pots) is also nonconductive polyurethane epoxy coated, to make it extremely difficult to get an accidental conductive pathway. The ultimate electrical safety analysis for fail-safe current relies on "Ohms Law" for determining Imax, based upon a Vmax ( ~ 4.8 VDC battery value) divided by the equivalent circuit current limiting resistance (R-limit) for the particular version being considered. 640N circuit schematics are available upon request for reviewing the maximum fail-safe current level.

640N Main Connector Test Lead Pinout /Socket Detail - Click here for a diagram that details the 640N Notched Main Connection Jack (diagrams/explains which pins and sockets are used for the 640 series Faraday cage, slimline Battery Charger and Test Leads).

Specifications
Accuracy: (180 days 25°C ± 10°C) ± 0.02% of reading  ± 0.02% of range for 20 ohm through 200 Kohm ranges. 1.0% of reading ±0.2% of range for 2.0 Megohm range.
Display: 4½ digit (19999) L.E.D.  - 20,000 counts (Display visible in direct sunlight (5 times brighter than high intensity LEDs))
Terminal Configuration: Four-wire Kelvin
Overload Indication: Display flashes
Maximum Input: 250 VDC or peak AC without damage
Operating Temperature Range: 0°C to 50°C
Temperature Coefficient: ±.002% per °C (from 0°C to 15°C and 35°C to 50°C)
Conversion Rate: Approximately 3 per second
Power: Rechargeable Ni-Cad batteries (5.0 Ahr) & Charger (115 VAC 50-60 Hz) (For Safety Reasons, the 640N Ohmmeter operation is electrically disabled and mechanically blocked (no mechanical access to the test lead connection) while charging the batteries).
Waterproof when submersed to a depth of 3 feet - with case and purge valve closed
Max. Internal Voltage: 4.8 VDC - 4 ea. 1.2 V   Ni-Cads
Size: 295mm/11.5" D x 335mm/13.5" W x 155mm/6" H
Weight: 12 lbs NET - 15 lbs shipping