Hampshire Controls LD-215 User Instructions

Liquid nitrogen level sensor

Hampshire Controls Corp.

1 Grove St.

Dover, NH 03820

(603) 749-9424 or Toll Free US/Canada (866) 496-9424

www.hampshirecontrols.com

LD-215 Liquid Nitrogen Level Sensor

User Instructions

Overview of Operation

The LD-215 uses a cryogenic RTD to sense the surface of

liquid nitrogen by monitoring the self-heating of the probe. The

alarm will sound and the output relay will change state when the

liquid level drops below the probe tip. In reverse mode, the

alarm will sound and the output relay will change state if the

liquid level makes contact with the probe tip.

The alarm can be silenced for a selectable period of time by

pressing the "MUTE" button. During mute the "ALARM" LED

will continue to flash and the output relay will stay in the "alarm"

condition. A return to normal liquid level will clear the alarm. See

page 2 for mute duration adjustment.

An alarm delay can also be specified. After the unit recognizes

an alarm condition, the green status "TIMING" LED will switch to

yellow and the unit will delay for the selected period before

alarming. See page 2 for alarm delay adjustment.

Any alarm condition, muted or not, will cause the relay to switch

to alarm state. The user can wire to the "Normally Open" (NO,

closed on alarm) or "Normally Closed" (NC, open on alarm)

contacts for external dialers, or other functionality.

Make sure the probe tip is fully submerged in liquid Nitrogen, wait 2 minutes for the probe temperature to

fully stabilize, press the RED push-button twice (pictured below). Observe the "TIMING" LED flash green

7 times to confirm successful setting of the new setpoint.

Table of Contents

Do you have a question about the LD-215 and is the answer not in the manual?

Page 1 LD-215 Liquid Nitrogen Level Sensor User Instructions Overview of Operation The LD-215 uses a cryogenic RTD to sense the surface of liquid nitrogen by monitoring the self-heating of the probe. The alarm will sound and the output relay will change state when the liquid level drops below the probe tip.
Page 2 ALARM CONTACT INPUT: Add a jumper to this pair of contacts to reverse the alarm function (Rarely used, high-level alarm).  Pt100 RTD: Input for LD-215 sensor, polarity is not important, factory installed.  6 TO 12 VOLTS DC: Positive (+) connection to power supply, factory connected.
Page 3 Insert the included batteries in the compartment at the back of the unit, please note the polarity. The LD-215 uses two rechargeable 1.2V NiMH AA cells for backup, and can run more than 24 hours on battery power. The batteries are continuously charged while the device is powered by the AC adapter. If AC power is lost for an extended period and the batteries state-of-charge becomes too low, the LD-215 will alarm.