LHe and LN2 level indicators
Lake Shore offers liquid helium and liquid nitrogen level indicators from top industry suppliers. Model specifications are listed below. If you do not have a preferred model, we will supply the indicator most appropriate for your system.
Model LM-510 liquid cryogen monitor
The LM-510 liquid cryogen level monitor is a compact instrument featuring all commonly requested functions controlled via the front-panel keypad.
Features of the LM-510:
- 240 × 400 TFT LCD display—the large viewing angle and high contrast multi-color display make it easy to see liquid cryogen levels and the status of alarms/refill cycle
- Full numeric keypad with directional arrows—unit setup is easier than ever with the expanded keypad
- Ethernet and USB computer connectivity standard
- 4 to 20 mA and 0 to 10 V analog output standard
- Options for IEEE-488.2 or RS-232
- Universal power input—100 to 240 VAC, 50 to 60 Hz
- Compact dimensions—7.25 in width × 2.50 in height × 7.00 in depth (184 mm × 64 mm × 178 mm)
The LM-510 also contains the most popular features of the LM-500:
- Configurable as a single channel unit to monitor liquid helium or liquid nitrogen
- Optional dual channel configuration can simultaneously monitor:
- Two liquid helium level sensors
- Two liquid nitrogen level sensors
- Or one of each
- Separate alarm (or refill setpoints) for each channel
- Sample and hold operation, burnout protection, and de-ice cycle for liquid helium level sensors
- level indication in centimeters, inches, or %
- Optional rack mount panel
- Optional line-voltage output controller used to automate liquid nitrogen refills
- Free LabVIEW® drivers
Model 110A liquid helium level meter
The low-cost Model 110A liquid helium level meter reliably measures the helium level in a Dewar. A 3.5 in analog display provides 0 to 100% liquid helium level indication. A 0 to 10 V recorder output is provided on the rear panel of the instrument. The Model 110A can be used with any AMI liquid helium level sensor up to 60 inches in active length.
Model 110A specifications
| Input power: | 90 to 132 VAC or 180 to 264 VAC, 50 to 60 Hz |
| Sensor current: | 75 mA |
| Linearity: | ±2% of full scale |
| Absolute calibration: | ±2% of full scale |
| Display: | 3.5 in analog meter |
| Recorder output: | 0 to 10 V standard (0 to 100 mV optional) |
| Dimensions: | 3.8 in H × 8.4 in W × 10.75 in D, standard (3.5 in H × 19 in W × 10.75 in D, rack mount) |
| Weight: | 4.0 lb standard; 4.7 lb rack mount |
Model 135 sample-and-hold level monitor
The Model 135 is an advanced liquid helium level monitor that incorporates AMI's patented sample-and-hold design with automatic helium level sensor vacuum burnout protection. The Model 135 is ideal for operation in systems where it is important to monitor the liquid helium level while also minimizing the helium losses.
Model 135 specifications at 25 °C
| Level measurements | |
| Resolution: | 0.1%, 0.1 cm, or 0.1 in |
| Accuracy: | ±0.5% of active sensor length |
| Linearity: | ±0.1% |
| Sensor current: | 75 mA nominal |
| Sensor voltage: | approximately 70 VDC for 80 in active sensor length |
| Operating parameters | |
| HI and LO alarms: | 0% to 100% adjustable |
| HI/LO alarm relay contact ratings: | 30 VAC or 60 VDC, 10 VA (up to 0.5 A max) [normally open, closed on alarm] |
| Sample-and-hold period: | 0.1 to 600.0 min (or h) |
| 0 to 10 V analog output | |
| Integral nonlinearity: | ±0.012% |
| Resolution: | 16 bits |
| Total error: | ±1.1% |
| Voltage drift (0 to 10 V): | 100 ppm/°C |
| 4 to 20 mA analog output at 24 V | |
| Vext supply range: | 13 to 32 VDC |
| Integral nonlinearity: | ±0.012% |
| Resolution: | 16 bits |
| Total error: | ±0.25% |
| Current drift (4 to 20 mA): | 75 ppm/°C |
| PSRR: | 10 µA/V |
| Power requirements | |
| Primary*: | 100 to 120 or 200 to 240 VAC ±10% 50 to 60 Hz, 50 VA |
| Physical | |
| Dimensions (standard): | 97 mm H × 213 mm W × 273 mm D (3.8 in H × 8.4 in W × 10.75 in D) |
| Weight (standard): | 1.8 kg (4.0 lb) |
| Dimensions (rack mount): | 89 mm H × 483 mm W × 273 mm D (3.5 in H × 19 in W × 10.75 in D) |
| Weight (rack mount): | 2.3 kg (5.0 lb) |
| Environmental | |
| Ambient temperature: | Operating: 0 °C to 50 °C (32 °F to 122 °F) Non-operating: -20 °C to 60 °C (-4 °F to 140 °F) |
| Relative humidity: | 0% to 95%, non-condensing |
*Maximum active sensor length is limited to 68 in for input line voltages below 105 VAC or 210 VAC.
Microprocessor-based electronics provide 0.1% readout accuracy. Nonvolatile, read-only memory maintains instrument calibration without battery backup. Watchdog timer circuitry and low line voltage (brownout) detector prevent microprocessor lock-up and provide fail-safe operation.
