Index: firmware/App/Controllers/ROPump.c
===================================================================
diff -u -re66245baae86e539e8470aa9739a99a2146d5f17 -r738afd1d72ec8da1c5bd347b9263a2c3ca2d8a61
--- firmware/App/Controllers/ROPump.c	(.../ROPump.c)	(revision e66245baae86e539e8470aa9739a99a2146d5f17)
+++ firmware/App/Controllers/ROPump.c	(.../ROPump.c)	(revision 738afd1d72ec8da1c5bd347b9263a2c3ca2d8a61)
@@ -54,6 +54,8 @@
 #define ROP_P_COEFFICIENT                   0.005               ///< P term for RO pump control
 #define ROP_I_COEFFICIENT                   0.0025              ///< I term for RO pump control
 
+#define FLOW_SENSOR_ZERO_READING            0xFFFF              ///< Flow sensor reading indicates zero flow (or flow lower than can be detected by sensor)
+
 #define FLOW_SAMPLES_TO_AVERAGE             (250 / TASK_PRIORITY_INTERVAL)              ///< Averaging flow data over 250 ms intervals.
 #define FLOW_AVERAGE_MULTIPLIER             (1.0 / (F32)FLOW_SAMPLES_TO_AVERAGE)        ///< Optimization - multiplying is faster than dividing.
 
@@ -155,7 +157,11 @@
         targetROPumpPressure.data = roPressure;
         roPumpControlMode = mode;
         // set PWM duty cycle target to an estimated initial target based on target pressure - then we'll control to pressure going forward
+#ifdef EMC_TEST_BUILD
+        roPumpPWMDutyCyclePct = 1.0;
+#else
         roPumpPWMDutyCyclePct = ROP_PSI_TO_PWM_DC( roPressure );
+#endif
 
         result = TRUE;
     }
@@ -195,7 +201,8 @@
  *************************************************************************/
 void execROPumpMonitor( void )
 {
-    S32 roFlow = (S32)getFPGAROPumpFlowRate();
+    U16 roFlowReading = getFPGAROPumpFlowRate();
+    S32 roFlow = (S32)roFlowReading;
 
     // update sum for flow average calculation
     measuredFlowReadingsSum += roFlow;
@@ -204,7 +211,14 @@
     {
         F32 avgROFlow = (F32)measuredFlowReadingsSum * FLOW_AVERAGE_MULTIPLIER;
 
-        measuredROFlowRateLPM.data = ( measuredFlowReadingsSum == 0 ? 0.0 : RO_FLOW_ADC_TO_LPM_FACTOR / avgROFlow );
+        if ( ( avgROFlow == FLOW_SENSOR_ZERO_READING ) || ( measuredFlowReadingsSum == 0 ) )
+        {
+            measuredROFlowRateLPM.data = 0.0;
+        }
+        else
+        {
+            measuredROFlowRateLPM.data = RO_FLOW_ADC_TO_LPM_FACTOR / avgROFlow;
+        }
         measuredFlowReadingsSum = 0;
         flowFilterCounter = 0;
     }
@@ -336,9 +350,11 @@
             F32 actPres = measuredROPumpPressure;
             F32 newPWM;
 
+#ifndef EMC_TEST_BUILD
             newPWM = runPIController( PI_CONTROLLER_ID_RO_PUMP, tgtPres, actPres );
             roPumpPWMDutyCyclePctSet = newPWM;
             setROPumpControlSignalPWM( newPWM );
+#endif
         }
         roControlTimerCounter = 0;
     }