Mini pH Controller - BL931700

In stock
The BL931700 is a compact single setpoint mini pH controller designed for applications where space and/or cost are important. It’s adjustable dosing relay may be configured to dose above or below a pH setpoint. Users may choose from automatic or manual dosing modes allowing for easy maintenance and troubleshooting. The device contains a high impedance pH input and may be used with any pH electrode that has a standard BNC connector.
  • Large Clear LCD
  • Fire Retardant Casing
  • BNC Connection


Enhanced Accuracy & Precision

The BL931700 model offers a manual two-point calibration with pH values displayed out to two decimal places.

External Disabling Feature

A normally open contact may connect to a level controller or flow monitor. This safety feature may be used to prevent continuous dosing in the event of specific or undesired system conditions.

Adjustable Dosing Relay

The BL931700 features a dosing relay which may be configured to dose above or below a user programmable pH setpoint.

Selectable Overdose Protection

The mini controller may be programmed to deactivate a valve, pump, or connected device if its activation continues over a selected time; adjustable from 5 to 30 minutes.

Selectable Control Override

With the flick of a switch, normal “Auto” operation may be overridden turning your connected device “Off” from operation or always “On.” 




Analog Output Communication

The BL931700 features a 4 - 20 mA analog output for connection to a data logger, chart recorder, or other device.

Matching Pin Connection

An included matching pin option helps protect the sensor from ground loop effects that may lead to erratic readings or system damage.

Fuse Protected Dosing Contacts

The mini controller is protected for up to a 2A load from the connected pump or device.

Easy Peripheral Connection

Quick-connect terminal blocks provide for easy connection to power, communication, dosing control, or sensors. 


Front View

Installation cut-out dimensions are provided as well as outside panel dimensions. 



Side View

Adjustable location brackets allow the controller to slide easily and securely into place.




pH Range

0.0 to 14.0 pH




±0.02 pH


manual, 2 points through offset and slope trimmers

Dosing Relay

maximum 2A (fuse protected), 250 Vac, 30 VDC

Dosing Selection

acid or alkaline contact open=acid dosage=relay ON if measurement > setpoint contact closed=alkaline dosage=relay ON if measurement < setpoint

Setpoint adjustable

from 0 to 14 pH


adjustable, typically from 5 to approximately 30 minutes

Input Impedance

10¹² Ohm

Analog Output

4 to 20 mA, accuracy ±0.20 mA, 500 ¥ maximum load

Power Supply

BL931700-0: 12 VDC adapter (included); BL931700-1: 115/230 VAC; 50/60Hz


83 x 53 x 99 mm (3.3 x 2.1 x 3.9’’)


BL931700-0: 200 g (7.1 oz.); BL931700-1: 300 g (10.6 oz.)

Ordering information

BL931700-0 (12 VDC) and BL931700-1 ( 115V) are supplied with mounting brackets, transparent cover and instruction manual.